forensic anthropology research definition

Forensic Anthropology

What do forensic anthropologists and detectives have in common.

Forensic anthropology is a special sub-field of physical anthropology (the study of human remains) that involves applying skeletal analysis and techniques in archaeology to solving criminal cases. When human remains or a suspected burial are found, forensic anthropologists are called upon to gather information from the bones and their recovery context to determine who died, how they died, and how long ago they died. Forensic anthropologists specialize in analyzing hard tissues such as bones. With their training in archaeology, they are also knowledgeable about excavating buried remains and meticulously recording the evidence.

Reading a Skeleton

A forensic anthropologist can read the evidence in a skeleton like you read a book. The techniques they use to answer questions in criminal cases can be applied to skeletons of any age, modern or ancient. The stages of growth and development in bones and teeth provide information about whether the remains represent a child or adult. The shape of pelvic bones provides the best evidence for the sex of the person. Abnormal changes in the shape, size and density of bones can indicate disease or trauma. Bones marked by perimortem injuries, such as unhealed fractures, bullet holes, or cuts, can reveal cause of death. The trained anthropologist is also able to identify skeletal clues of ancestry. Even certain activities, diet, and ways of life are reflected in bones and teeth.

Analyzing Human Remains

Anthropologists at the Smithsonian’s National Museum of Natural History have been called upon to analyze human remains for over a century. The remains may represent victims of violence or natural disasters. In these cases Smithsonian anthropologists work with the FBI , State Department, and other law enforcement agencies to identify the individuals and solve crimes. They also conduct research on historic and prehistoric human remains to learn more about people from the past. As Smithsonian forensic anthropologist Kari Bruwelheide says, "The bones are like a time capsule."

Smithsonian anthropologist Dr. Douglas Owsley , examining a skeleton from historic Jamestown , discovered evidence of chops to the skull from an axe or other sharp bladed, implement. Knife cuts were also observed on the bone. Along with other information such as biological indicators and discovery location of the remains, Dr. Owsley concluded that a 14-year-old girl had been cannibalized after she died. His discovery supported other historic data that the colonists of Jamestown suffered severe starvation during the harsh winter of 1609-1610.

Techniques: Leaving No Bone Unturned

Anthropologists at the National Museum of Natural History use a variety of techniques to analyze human remains and record their observations. For example, the bones are typically photographed and X-rayed. Some remains may undergo CT scanning or be examined with high-powered microscopes. These techniques provide detailed information about remains without altering them while providing a visual record. DNA analysis may be used to help establish identity. This type of testing is most often used in modern forensic case work, but mitochondrial DNA in bones and teeth can be used to confirm relationships of old remains with deceased or living descendants. Other chemical analyses, such as those involving isotopes, can provide information about the age of bones and a person’s diet.

The data gathered is studied and combined to draw conclusions about the deceased individual. For a modern case, photos of the skull may be superimposed on photos of missing people to look for consistencies between the bone and fleshed form. Even in cases where no photos exist, the face can be reconstructed based on the underlying bone structure and known standards of facial tissue thicknesses. For example, using facial reconstruction, Smithsonian forensic anthropologist Dr. David Hunt was able to bring about correct identification of the remains of a child found near Las Vegas. Owsley and Bruwelheide were able to help rebuild the likeness of the girl from Jamestown .

Collections of Bones

Comparing found remains to other human skeletons is essential for many analyses. The National Museum of Natural History has one of the world's largest Biological Anthropology collections , with over 30,000 sets of human remains representing populations from around the world. Many of the skeletons have associated age, sex, ancestry, and cause of death data. Individual remains with known biological information are especially valuable references. Forensic anthropologists have used these skeletons to develop standards for determining sex, age and ancestry in unknown remains. The bones and teeth are also used as comparative materials in cases where interpretation of certain features is difficult. They are also used to train students who are the next generation of biological anthropologists. Skeletal reference series may also be used to document trends in health and population structures over time. Smithsonian Curator Dr. Douglas Ubelaker , looking at a range of skulls from 16th-20th century Spain and Portugal, found that women's faces got larger over time.

Reconstructing the Past

The study of historic human remains by biological anthropologists at the Smithsonian has led to discoveries that are changing our view of the past and how we investigate it. The work of Dr. Owsley and Kari Bruwelheide has helped create a better picture of how people lived and died in colonial America. For example, even a wealthy woman, the wife of the governor of Maryland's first English colony, St. Mary's City, suffered from limited medical care for a fractured thigh bone. The sorts of treatments that would be used today (traction and screws), were not options at the time. Available treatments, such as medicine containing arsenic, may have made conditions worse. Chemical testing of this woman's preserved hair show ingestion of this toxin with increasing dosage closer to death.

Whether used to better understand modern or historic remains, the tools and techniques of forensic anthropology give the living a window into the lives of the dead.

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Forensic anthropology is the scientific study of human skeletal remains in the context of crime or medico-legal contexts. It is a fairly new and growing discipline that is made up of several branches of academic disciplines brought together to assist in legal cases involving the death and/or identification of individual people.

Key Takeaways: Forensic Anthropology

Forensic anthropology is the scientific study of human skeletal remains in the context of crime or natural disaster .
Forensic anthropologists participate in many different tasks during such investigations, from mapping the crime scene to positively identifying the individual from the skeleton.
Forensic anthropology relies on comparative data housed in donated repositories and digital data banks of information.

The primary focus of the profession today is determining the identity of a dead person and the cause and manner of that person's death . That focus can include extracting information about the individual's life and condition at death, as well as identifying characteristics revealed within the skeletal remains. When there is soft body tissue still intact, a specialist known as a forensic pathologist is required.

The profession of the forensic anthropologist is a relatively recent outgrowth from the broader field of forensic sciences in general. Forensic science is a field which has its roots at the end of the 19th century, but it didn't become a widely practiced professional endeavor until the 1950s. Early anthropologically-minded practitioners such as Wilton Marion Krogman, T.D. Steward, J. Lawrence Angel, and A.M. Brues were pioneers in the field. Sections of the field dedicated to anthropology — the study of human skeletal remains — began in the United States in the 1970s, with the efforts of pioneer forensic anthropologist Clyde Snow.

Forensic anthropology began with scientists dedicated to determining the "big four" of any one set of skeletal remains: age at death, sex , ancestry or ethnicity , and stature . Forensic anthropology is an outgrowth of physical anthropology because the first people who attempted to determine the big four from skeletal remains were primarily interested in the growth, nutrition, and demography of past civilizations .

Since those days, and largely due to an enormous number and variety of scientific advances, forensic anthropology now includes the study of both the living and the dead. In addition, scholars strive to collect information in the form of databases and human remains repositories, that allow continuing research in the scientific repeatability of forensic anthropological studies.

Forensic anthropologists study human remains, with particular respect to the identification of the individual person from those remains. Studies include everything from single homicide cases to mass death scenarios created by terrorist activities such as the World Trade Center on 9/11 ; mass transit crashes of planes, buses, and trains; and natural disasters such as wildfires, hurricanes, and tsunamis.

Today, forensic anthropologists are involved in a wide range of aspects of crimes and disasters involving human deaths.

Scene of the crime mapping — sometimes known as forensic archaeology, because it involves using archaeological techniques to recover information at crime scenes
Search and recovery of remains — fragmented human remains are difficult for non-specialists to identify in the field
Species identification — mass events often include other life forms
Postmortem interval — determining how long ago the death occurred
Taphonomy — what kinds of weathering events have affected the remains since the death
Trauma analysis — identifying the cause and manner of death
Craniofacial reconstructions or, more properly, facial approximations
Pathologies of the deceased—what kinds of things did the living person suffered from
Positive identification of human remains
Acting as expert witnesses in court cases

Forensic anthropologists also study the living, identifying individual perpetrators from surveillance tapes, determining the age of individuals to define their culpability for their crimes, and determining the age of subadults in confiscated child pornography.

A Wide Range of Tools

Forensic anthropologists use a wide range of tools in their business, including forensic botany and zoology, chemical and elemental trace analysis, and genetic studies with DNA . For example, determining the age of death can be a matter of synthesizing the results of what an individual's teeth look like — are they fully erupted, how much are they worn — combined with other metrics considering things like the progression of epiphyseal closure, and the centers of ossification — human bones become harder as a person ages. Scientific measurements of bones may be achieved in part by radiography (photo-imaging of the bone), or histology (cutting cross-sections of the bones).

These measurements are then compared against databases of previous studies of humans of every age, size, and ethnicity. Human remains repositories such as those at the Smithsonian Institution and the Cleveland Museum of Natural History were assembled by scientists in the 19th and early 20th centuries largely without the consent of the culture being collected. They were incredibly important to the early growth of the field.

However, beginning in the 1970s, shifts in political and cultural power in western societies have resulted in the reburial of many of these remains. The older repositories have largely been supplanted by collections of donated remains such as those at the William M. Bass Donated Skeletal Collection , and digital repositories such as the Forensic Anthropology Data Bank , both of which are housed at the University of Tennessee at Knoxville.

Significant Studies

The most publicly visible aspect of forensic anthropology, outside of the wildly popular CSI series of television shows, is the identification of historically important persons. Forensic anthropologists have identified or attempted to identify people such as the 16th-century Spanish conquistador Francisco Pizarro , the 18th-century Austrian composer Wolfgang Amadeus Mozart, the 15th-century English king Richard III, and the 20th-century U.S. president John F. Kennedy . Early mass projects included identifying the victims of the 1979 DC10 crash in Chicago; and the ongoing investigations into Los Desaparecidos, thousands of missing Argentine dissidents murdered during the Dirty War.

Forensic science is not infallible, however. Positive identification of an individual is limited to dental charts, congenital abnormalities, unique features such as previous pathology or trauma, or, best of all, DNA sequencing if the likely identity of the person is known and there are living relatives who are willing to help.

Recent changes in legal issues resulted in the Daubert standard, a rule of evidence for expert witness testimony agreed upon by the U.S. Supreme Court in 1993 (Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 584-587). This decision affects forensic anthropologists because the theory or techniques that they use to testify in court cases must be generally accepted by the scientific community. In addition, the results must be testable, replicable, reliable, and created by scientifically valid methods developed outside of the current court case.

" Anthropologists and Archeologist ." Occupational Outlook Handbook . U.S. Bureau of Labor Statistics, U.S. Department of Labor 2018. Web.
Blau, Soren, and Christopher A. Briggs. " The Role of Forensic Anthropology in Disaster Victim Identification (DVI) ." Forensic Science International 205.1 (2011): 29-35. Print.
Cattaneo, Cristina. " Forensic Anthropology: Developments of a Classical Discipline in the New Millennium ." Forensic Science International 165.2 (2007): 185-93. Print.
Dirkmaat, Dennis C., et al. " New Perspectives in Forensic Anthropology ." American Journal of Physical Anthropology 137.47 (2008): 33-52. Print.
Franklin, Daniel. " Forensic Age Estimation in Human Skeletal ." Legal Medicine 12.1 (2010): 1-7. Print. Remains: Current Concepts and Future Directions
Yaşar Işcan, Mehmet. " Rise of Forensic Anthropology ." American Journal of Physical Anthropology 31.9 (1988): 203-29. Print.
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Article Contents

Molecular analysis of skeletal evidence, migrant identification, search, detection and recovery, commingling analysis, biomechanics of bone trauma, decomposition research, bone microscopy, isotope analysis, facial imaging, recent advances in forensic anthropology.

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Douglas H. Ubelaker, Recent Advances in Forensic Anthropology, Forensic Sciences Research , Volume 3, Issue 4, December 2018, Pages 275–277, https://doi.org/10.1080/20961790.2018.1466384

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Forensic anthropology involves diverse applications of anthropological knowledge to medico-legal problems. While the applications are evidence-driven, the available scientific methodology and foundation have developed through decades of research and experience. The roots of this field are anchored in comparative human anatomy but methodology has developed through experimentation, the assemblage of documented collections and databases and thoughtful research design. While forensic anthropology represents a mature scientific field, it continues to evolve and advance through new, innovative global research. Much of this progress is fuelled by issues encountered in casework. The unique evidence and problems presented in forensic cases call for the very best scientific approaches available. Usually, the correct approaches and solutions can be found in the existing scientific literature. However, sometimes the unique issues presented by the casework cannot be addressed adequately with the existing techniques. These situations stimulate forensic anthropologists to seek new solutions through targeted research.

This Special Issue presents research advances in several areas of forensic anthropology that have sustained rapid, recent progress. While our journals continually reveal new information in all aspects of forensic anthropology, several areas of investigation have registered particularly strong academic interest featuring innovative research.

Successful recovery and analysis of DNA has dramatically affected many areas of forensic science. In the field of forensic anthropology, molecular analysis can yield highly accurate information regarding the sex of the individual represented and provide positive identification [ 1 ]. Molecular approaches also can contribute to ancestry evaluation and species recognition. The use of DNA for positive identification has had a major impact on the practice of forensic anthropology and related fields of forensic science.

While the merits and contributions of DNA analysis are profound, many related issues express the need for new, innovative research and technological development. Frequently, evidence submitted for forensic anthropological analysis is not in pristine condition. In many cases, recovered remains are incomplete and/or extremely degraded due to criminal activity and/or taphonomic factors. Some site investigations produce only small fragments where even species is not apparent. Decisions need to be made regarding what areas of bone or tooth should be examined. Since DNA analysis is an expensive and destructive process, these decisions are critical and can affect the outcome of the case. Of course, decisions regarding the type of DNA analysis also are critical and largely driven by both the availability of the antemortem information and the nature of the evidence. Experimentation and casework experience have greatly improved approaches to these issues.

Deaths related to the global movement of undocumented people across national borders present major forensic challenges. Even within countries, identification of citizens can be difficult with incomplete evidence and lack of information regarding missing persons. These problems are greatly exacerbated when different countries are involved and the international movement of the person represented is not registered officially. Such cases call for extraordinary investigation, thoughtful forensic analysis and international communication. These efforts can strain the available local resources and often fall short of positive identification.

Recent years have witnessed remarkable efforts to address the identification of deceased, undocumented border crossers. These initiatives have involved international cooperation, careful exhumation procedures, comprehensive anthropological analysis and new techniques such as isotope analysis to identify the likely regions/countries of origin.

The entire process of forensic anthropological investigation begins with the procedures of search, detection and recovery. Improper or inadequate detection and recovery of human remains can compromise the downstream analysis and interpretation. While the traditional techniques of surface survey and excavation continue to be needed, new approaches, especially those using advanced technology offer significant advances.

Search procedures can be especially challenging when only very general information is available regarding the likely location of human remains. Topographic features can present limitations, especially with dense vegetation and other ground cover. Investigations of humanitarian and human rights issues can present special search and recovery challenges when information suggests that wells, cisterns, sewer systems, mass graves or disposal in water were involved. Confronted with these problems, researchers have devised innovative new approaches to improve the probability of success.

Secondary deposits of human remains or those that have sustained significant disturbance involve loss of normal bone articulation patterns. When multiple individuals are involved, the resulting commingling presents challenges to determine the number of persons represented and to assemble remains of individuals for analysis, identification and return to families. Traditional approaches to commingling problems have involved sorting by the type and side (left or right) of bone, age at death, bone size and maturation, sex and pathological conditions. In some skeletal assemblages, taphonomic indicators can be helpful as well.

Once obvious sorting has been completed, questions persist regarding bone morphology related to individuals. Could a robust femur relate to a robust humerus and represent one individual? Recent advances in commingling analysis address this issue. New databases and computerized techniques establish the probabilities that different bones could relate to the same individual. Applications refine the determination of the number of individuals represented and facilitate analysis aimed at identification.

A primary function of anthropological analysis relates to the interpretation of bone trauma. Anthropologists must differentiate the skeletal alterations representing perimortem trauma from those relating to antemortem injury, developmental features or postmortem and taphonomic factors. Assessment of the biomechanical factors involved plays a key role in any interpretation. Knowledge of biomechanical principles is required to explain fracture patterns and other alterations likely related to perimortem trauma. Interpretation of bone trauma can be challenging. Such challenges have led to greater understanding of the principles involved and experimental work designed to improve interpretation.

Major new initiatives in forensic anthropology have focused on decomposition research. Experiments involving both humans and non-human animals have revealed great detail about the process and variation of soft tissue decomposition and hard tissue alteration. In general, such research has elucidated the many factors that influence both the nature and timing of the decomposition process. Clearly temperature and location (surface, in-ground, aquatic, etc.) have long been regarded as key factors. Research has also indicated that soil conditions, moisture, body composition, body condition, presence of clothing or enclosures, funerary treatment and many other factors can influence the process. Such information is needed to properly assess time since death (post-mortem interval) and post-mortem events related to criminal activity.

In 1965, Ellis R. Kerley [ 2 ] published a technique that allowed age at death to be estimated from microscopic examination of features in human compact bone from the femur, tibia and fibula. Kerley's procedure involved the examination of primary osteons, secondary osteons, osteon fragments and the extent of remaining circumferential lamellar bone. This approach gained recognition due to its reported accuracy and the fundamental processes of bone formation and remodelling that it expressed. Since 1965, the technique has undergone many revisions and expansions for application to other bones of the skeleton. Research also has revealed how bone microscopic examination can provide useful information on many issues of forensic anthropological analysis.

For decades, analysis of elemental stable isotopes has offered key anthropological information related to diet. Stable carbon isotopes recovered from human tissues have revealed if diet focused on plants with a C 3 photosynthetic pathway or a C 4 pathway and the herbivores that fed upon them. Analysis of nitrogen isotopes provides insight into the trophic level of human diet. In anthropological studies of ancient populations, such information is crucial to interpretations of dietary and horticultural practices.

Recently, researchers have applied the concepts of isotopic analysis to examine the geographical origin of human remains. When unidentified human remains are recovered in forensic contexts, investigators question if they represent someone who lived in the area of recovery or from somewhere else. This question is especially relevant in cases involving terrorism and unidentified possible migrants. Using a battery of stable isotope analyses, researchers can determine if the isotopic signatures from the unknown match local baseline data. If not, attempts can be made to determine from what geographic area the unknown originated. This exciting new area of forensic science investigation depends on the assemblage of baseline data from appropriate geographic regions.

Forensic anthropologists relate to issues of facial imaging in facial approximation, craniofacial photographic superimposition and interpretations of surveillance images. Facial approximation refers to the process of estimating the living facial image of a person from the evidence presented by a recovered skull. This technique is used to reach out to the public for leads in missing persons that could culminate in identification using other methods.

Craniofacial photographic superimposition involves comparing a facial photograph of a missing person with a recovered skull. This technique is used primarily to exclude when photographs are available of a missing person thought perhaps to be represented by the recovered remains.

Recent research has focused on enhanced use of computers and related technology, as well as targeted efforts to clarify the relationship between soft and hard tissues. Facial approximation continues to represent a blend of art and science; however, recent advances have strengthened the scientific foundation.

Articles in this Special Issue of Forensic Sciences Research focus on overviews of the published literature on these topics. They also share results from the latest innovative research on these key areas of forensic anthropology applications.

Baker L . Biomolecular applications . In: Blau S Ubelaker DH , editors. Handbook of forensic anthropology and archaeology . 2nd. ed. New York: Routledge ; 2016 . p. 416 – 429 .

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Kerley ER . The microscopic determination of age in human bone . Am J Phys Anth . 1965 ; 23 : 149 – 163 .

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An ABFA Diplomate leads a search and recovery exercise

What is Forensic Anthropology?

Generally speaking, Forensic Anthropology is an applied area of physical (i.e., biological) anthropology; it specifically uses the science, methodology, and technology of physical/biological anthropology and related fields to help address medicolegal issues, such as personal identification and circumstances surrounding death. Forensic Anthropologists use clues from the skeleton to assist medical examiners and coroners on a variety of cases, typically including those involving skeletal remains, fragmentary or decomposing remains, burned bodies, buried remains, and child abuse, as well as other trauma cases. More specifically, Forensic Anthropologists use their knowledge of the human skeleton, archaeological methods, and the decomposition process to:

Determine if skeletal remains are human or nonhuman, and if human, whether they are medicolegally significant., search for and recover remains using modified archaeological methods. forensic anthropologists may also apply the same skill set to contexts outside of a medicolegal death investigation. for example, they may work for a government agency tasked with recovering and identifying the remains of fallen service members or for a non-governmental organization investigating human rights abuses in domestic or international contexts., assist in identifying deceased individuals who cannot be immediately identified through traditional means (such as by visual recognition, fingerprints, or dental evidence)., examine remains for signs of trauma in order to aid in determining what happened to the deceased individual at the time of or even before death., determine how long ago the individual died by examining the condition of the remains. f orensic anthropologists may work directly with forensic pathologists in a medical examiner or coroner system, or they may be consulted on an as-needed basis..

What is an ABFA Diplomate?

An American Board of Forensic Anthropology (ABFA) Certified Forensic Anthropologist is an expert who demonstrates the maximum level of professional qualifications in forensic anthropology. The highest level of education and experience in the discipline is required.

Each diplomate: , has passed a rigorous application, evaluation, and examination process in forensic anthropology. included are comprehensive vetting of the candidate’s education, training, and experience, as evidenced by their body of casework, curriculum vitae, and letters of reference. knowledge, competency, and skill are assessed through written and practical examinations. the successful completion of all entitles an applicant to be known as a diplomate of the american board of forensic anthropology (d-abfa), demonstrates outstanding and sustained involvement in professional forensic anthropology activities including casework, court testimony, research, publications, teaching, continuing education, and public service, adheres to the highest moral, ethical, professional, and personal standards (as reflected by the abfa ethics statement), is required to recertify every three years to maintain diplomate status, uses standards, guidelines, and appropriate methodology to demonstrate the highest professional and best practice competencies, abilities, and skills in the major areas of forensic anthropology, including:, methods to estimate the biological profile , trauma interpretation and biomechanical principles , anatomy, bone and tooth growth and development, osteology, and bone histology , pathological conditions , individualizing anomalous skeletal characteristics , minimum number of individuals, taphonomy and postmortem interval , determination of medicolegal significance , scene processing, evidence handling, court procedures, legal concerns, and courtroom testimony, statistical analyses , positive identification of decedents in single or mass fatality events, completion of clear, concise, and accurate case reports, how forensic anthropologists contribute to death investigations.

Bioarchaeology, Human Osteology, and Forensic Anthropology: Definitions and Developments

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Ubelaker, D.H. (2014). Bioarchaeology, Human Osteology, and Forensic Anthropology: Definitions and Developments. In: Smith, C. (eds) Encyclopedia of Global Archaeology. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-0465-2_126

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1 Definition, Aim and Scope of Forensic Anthropology

The text is divided into four different parts that includes:

Introduction
Historical Development of Forensic Anthropology
Definition of Forensic Anthropology
Scope of Forensic Anthropology

Learning Objectives:

Through this text, one will be able to know about forensic anthropology, a specialized, applied branch of physical/biological anthropology which deals with the medico-legal investigation.
How it has been developed a sub-discipline of biological anthropology through historical dimension is also stated in this text. Further, definitions of forensic anthropology by different authors have been given for scientific understanding of forensic anthropology.
The provided text explains scope of forensic anthropologist as well as work of forensic anthropologists how they are helpful for the court of law or law enforcement agencies.

1. Introduction

Human beings have always been curious about its surrounding, fellow creatures, cosmology and no less about its own existence. This curiosity of man takes him to the roots of history, the cobwebs of polities, biology and plethora of other field of study. However, anthropology is an amalgamation rather says a beautiful patchwork of many branches of science and humanities. Anthropology answers the questions of human’s past and present, and these answers are not based upon the free spirited human imaginations, rather those findings are the resultant facts of undaunted labor and intellect. Anthropology builds a knowledge base which has different dimensions encompassing a plethora of subjects and streams. It not has theoretical aspects but also applies it knowledge base in solution of societal problems. Simply put, it is study of human being with time and space. Anthropology is a subject divided into following branches-

Physical / Biological anthropology
Social / cultural anthropology
Archaeology
Linguistic Anthropology

Physical/biological anthropology sees the physical development of human being. Biological /physical anthropology deals with different processes of the human environment and the way human has been dealing with it ever since the advent of life forms. It deeply studies how human lives are affected by the outer environment and social milieu. It studies the human evolution with various stages, the factors affecting that process, the detriments i.e. disease and so on, and very practically subsequently the cause and remedial measures of those detriments are also the part of the study of physical anthropology. Thus physical anthropology has more cutting edge level perspectives and utility in everyday life also.

Society has many components live human, culture, resources, etc. Human being is a social animal and there is a fusion process. It means human beings on affected by society and in return in affects on it. There are political society i.e. country or state & Natural society i.e. family. These societies are also intertwined.

Archaeology is the expression and capability of human to create to build. It is creativity and it is through process at a given point of time. It has a temporal process at a given point of time. It has a temporal dimension too. Bio-archaeology adopts a population-oriented approach and typically involves the examination of human remains and artifacts from an entire historic or prehistoric cemetery.

Language is the medium of expression. Through words we connect to each other, language has the symbols which carry our expression. In Hindu mythology, “The Word” is given utmost importance as Upanishads ray “Shabdoeyambhram ”. It is equivalent to God – So, language is one of the most vital components of our culture, society and to the very existence of human beings. Thus, Linguistic anthropology amalgamate anthropology including it all branch i. e. biological, socio-cultural and archeological anthropology.

When a human body is discovered, the primary objectives in an investigation are to identify the victim and to establish the cause and manner of death. If the remains are found relatively soon after death, these goals are usually accomplished by the law enforcement agency and the forensic pathologist performing the autopsy. When the remains are not discovered until sometime after death, however, the expertise of a forensic anthropologist is often needed. In cases involving skeletal remains, it is the forensic anthropologist who can best establish a profile of age, ancestry, sex, and stature and provide an assessment of trauma (Gretchen and Ubelaker, 2001).

Thus, Forensic anthropology is the sub-branch of biological anthropology which uses the anthropological knowledge and application for medico-legal process. Forensic anthropology encompasses the field recovery of partly or completely skeletonised remains and their laboratory management and analysis. It involves the determination of whether the skeletal remains are of animal or human origin; the number of individuals represented; the race, sex, age and stature of the individuals concerned; the pathology, injuries and anomalies that are present; the identification of unique individual characteristics; the estimation of the time since death and manner and cause of death; and the investigation of the individual’s identity by matching of post-mortem skeletal evidence with ante-mortem records or portraits (Wood et al,2002). Forensic anthropology forms an integral component of an investigative team in the field, laboratory, and courtroom. For example, during the identification process, forensic anthropologists may work with police investigators, crime scene technicians, forensic pathologists, odontologists (dentists), molecular geneticists, radiologists, and fingerprint experts. New members are added to the team if a case goes to trial, including the attorneys and a variable number of additional forensic specialists, such as ballistics experts, trace evidence examiners, and document examiners, each of whom testifies as to his or her scientific or technical findings (Steadman, 2008). Forensic Anthropologist is helpful for the Court of Law as follows:

Human or not
Individual Identification
Minimum number of individuals
Age Determination
Sex Determination
Number of Individuals
Disease Processes

2. Historical Development of Forensic Anthropology

Thompson (1982) distinguished three periods in the development of forensic anthropology: pre-1939, 1939-1972, and post-1972. Forensic anthropology has its roots principally in the anatomical sciences. Before 1939, anatomy departments were the principal contributors to the methodology of human skeletal variation, using collections of cadavers of known age, ancestry, sex, and morbidity. Undoubtedly, at this time, physical anthropologists and anatomists were consulted by law enforcement agencies regarding skeletal remains. Thomas Dwight (1843-1911) of Harvard University, H.H. Wilder (1864-1928) of Smith College in Massachusetts of the Field Columbian Museum in Chicago were among those anthropologists interested in the forensic aspects of anthropology (Stewart, 1979). During this same period, Earnest Hooton (1887-1954) of Harvard University and Ales Hrdlicka (1869-1943) expressed interest in the field. Among the contributions made by Hrdlicka was his key role in the founding of the American Association of Physical Anthropologists in 1930 and the American Journal of Physical Anthropology in 1918. Hrdlicka also consulted with law enforcement agencies, including the FBI, on a number of skeletal cases (Ubelaker, 1999a, 1999b). Hooton later publish “Medico-legal Aspects of Physical Anthropology” in Clinics, in which he described the dim prospect of new methods in the field of physical anthropology in a forensic context, undoubtedly because of the lack of attention given to the field (Hooton, 1943). In 1939, W.M. Krogman published “A Guide to the Identification of Human Skeletal Material” in the FBI Law Enforcement Bulletin, marking the beginning of the second period of forensic anthropology development. This publication represented the first major contribution by a trained anthropologist on the topic of human skeletal identification for medico-legal purposes. Krogman’s publication allowed the forensic community, as well as other physical anthropologists, to view physical anthropology in a forensic context (Stewart, 1979). At the close of World War II, several physical anthropologists were consulted in the identification of war casualties. Among the anthropologists who contributed their expertise were H.L. Shapiro of the American Museum of Natural History in New York, F.E. Randall of the U.S. Army’s Office of the Quartermaster General, and Charles Snow of the University of Kentucky. Krogman’s “Guide” became a manual used by the anthropologists in the identification process. A central laboratory was established for this purpose in 1947 in Hawaii and was headed by Charles Snow (Gretchen and Ubelaker, 2001). Not long before, in the early 1940s, T.D. Stewart began his routine consultation with the FBI for forensic skeletal cases (Ubelaker, 1990). This relationship, initiated by Hrdlicka, represented an early phase of a long history of collaboration between the FBI and the Smithsonian.

In 1962, Krogman wrote the first textbook on forensic anthropology, “The Human Skeleton in Forensic Medicine” (revised and updated: Krogman and Iscan, 1986), is a compilation of techniques and case histories of the identification of human remains. In the text, Krogman identified methods for the determination of age, ancestry, sex, and stature, as well as individualizing characteristics and restoration of facial features on the skull. A turning point for forensic anthropology came in 1972 when American Academy of Forensic Sciences (AAFS) instituted the Physical Anthropology section. Section was the increase in the number of textbooks on forensic anthropology. In 1979, Stewart published Essentials of Forensic Anthropology. This textbook was the first to include a chapter on courtroom procedures associated with expert testimony. The post-1972 era marked an emergence of material written by anthropologists for other anthropologists and, equally as important, for other scientists and law enforcement personnel. Current literature in forensic anthropology encompasses a wide range of topics and issues. Anthropologists are no longer limited to research involving the estimation of age, ancestry, sex, and stature, as was prominent during the emergence of the field. Although a large amount of research is still being conducted on improving and testing these techniques, the anthropologist’s scope has reached far beyond them (Galloway et al., 1993). Hrdlicka was a pioneer in American physical anthropology and played a key role in founding the American Association of Physical Anthropologists and its journal, the American Journal of Physical Anthropology. Although Hrdlicka is best known for his study of the peopling of the new world and anthropometry, his research interests and activities were broad and included forensic topics. Hrdlicka’s training included legal medicine, and his early work focused on forensic issues regarding the biological basis for abnormal behavior. At the Smithsonian’s Department of Anthropology, he became involved in legal issues relating to American Indian ancestry and skeletal analysis. Perhaps as early as 1918, the FBI became aware of Hrdlicka’s expertise, and at least by 1936, the FBI began to send specimens to Hrdlicka for identification (Ubelaker, 1999a).

Seeds of what was to become forensic anthropology were sown in France with the work of Jean-Joseph Sue, an instructor of art anatomy at the Louvre in Paris. In 1755, he published measurements of cadavers ranging in age from fetus to young adult. Although the intention was to provide artists with accurate information on body proportions and how such proportions changed with age, the work launched an important French interest, leading to research on stature calculation. Sue’s measurements reached a wider audience through publication by Mathieu-Joseph-Bonaventure Orfila in two medico-legal textbooks in the early 19th century. Orfila (1831) supplemented Sue’s measurements with his own, and for many years, the two databases comprised the sources used by the medico-legal community to evaluate stature from incomplete remains.

3 . Definition of Forensic Anthropology

Forensic anthropology encompasses the field recovery of partly or completely skeletonized remains and their laboratory management and analysis. It involves the determination of whether the skeletal remains are of animal or human origin; the number of individuals represented; the race, sex, age and stature of the individuals concerned; the pathology, injuries and anomalies that are present; the identification of unique individual characteristics; the estimation of the time since death and manner and cause of death; and the investigation of the individual’s identity by matching of post-mortem skeletal evidence with ante-mortem records or portraits.

In 1939 W.M. Krogman published ‘A Guide to the Identification of Human Skeletal Material’ and the “Human Skeleton in Forensic Medicine (1962). This published work was used by other anthropologist for development of forensic anthropological methods.

Krogman’s guide was followed by T.D. Stewarts 1979 book ‘The Essentials of Forensic Anthropology: Especially as Developed in the United States’, and then in 1986 Krogman and M.Y. Iscan defined the ‘big four’ in forensic anthropology for identification of skeletal remains in criminal investigations: age, sex, race, and stature. This provided the foundation, from which Forensic Anthropology has developed, and since then numerous texts and articles have been published, and research occurs around the world.

Snow (1973) offered a somewhat broader definition of forensic anthropology to include applications to “problems of medical jurisprudence.”

In 1976, T. D. Stewart defined forensic anthropology as “that branch of physical anthropology, which, for forensic purposes, deals with the identification of more or less skeletonized remains known to be, or suspected of being, human”.

Forensic anthropology represents the application of knowledge and techniques of physical anthropology to problems of medico-legal significance. Goals are usually to assist in the identification of human remains and to help determine what happened to the remains, especially with regard to the evidence of foul play. Usually, the material examined consists of largely or completely skeletonized remains, or skeletal evidence that has been removed from fleshed remains. Forensic anthropology brings to a case techniques and experience in the interpretation of skeletal remains as well as a worldwide comparative population perspective (Ubelaker, 1996).

Forensic anthropology is defined as the application of anthropological and skeletal biological principles to medico-legal issues. The term medico-legal refers to the capability of medical science to shed light on legal matters, such as the identity of the deceased and the circumstances of death (Fisher 2003).

The American Board of Forensic Anthropology provides the following definition and additional clarifying information on forensic anthropology:

Forensic anthropology is the application of the science of physical or biological anthropology to the legal process. Physical or biological anthropologists who specialize in forensics primarily focus their studies on the human skeleton.

4 . Scope of Forensic Anthropology

Forensic anthropologists do analysis of skeletal, badly decomposed, or otherwise unidentified human remains is important in both legal and humanitarian contexts.
Forensic anthropologists apply standard scientific techniques developed in physical anthropology to analyse human remains, and to aid in the detection of crime.
In addition to assisting in locating and recovering human skeletal remains, forensic anthropologists work to assess the age, sex, ancestry, stature, and unique features of a decedent from the skeleton.
Forensic anthropologists frequently work in conjunction with forensic pathologists, odontologists, and homicide investigators to identify a decedent, document trauma to the skeleton, and/or estimate the post-mortem interval (ABFA 2008:1).

Forensic Anthropologists are helpful for the investigation of crime /crime scene because of their training in cultural anthropology, archaeology, taphonomy and biological anthropology. Their training in cultural anthropology allows them to identify cultural markers that define ethnic, religious or national groups. Their training in anthropology, archaeology and taphonomy gives them the skills needed to excavate clandestine graves and crime scenes where any incident occurred (Byers 2005). In particular, taphonomy, or “the interpretation of all events affecting the remains between death and discovery represents the most important contributions made by anthropologists (Ubelaker 1997:80). Their training in biological anthropology gives them the skills needed to analyze skeletal remains and the associated material needed to prove genocide (Byers 2005).

When examining the surreptitious graves and remains of murder victims, the forensic anthropologist help in solving the problem as follows:

First, determine various demographic attributes of the victim such as ancestry or ethnic group, sex, age, and stature of the individual.
Second, collect evidence of traumatic injury to determine the nature and cause of the trauma to assist in the determination of the manner of death.
Third, based on knowledge of decomposition and deterioration of human remains after death, estimate the time that passed since the individual died, or the post-mortem interval (PMI).
Fourth, assist in the location of remains buried or left on the surface of the ground in a way that allows the collection of all relevant evidence needed for the forensic investigation.
Fifth, using knowledge of skeletal features, forensic anthropologists can provide information unique to each individual to obtain a positive identification (Byers 2005; Cattaneo 2007).
Additionally, the practice of forensic anthropology can be seen as a clinical practice because it employs both clinical and actuarial judgment. Clinical judgment requires the practitioner to process information learned from both academic training and hands-on or clinical analysis of human remains. In contrast, actuarial judgment requires interpretations based on calculations using empirically established formulas (Klepinger, 2006).

Conclusion: Forensic Anthropologists play an important role in establishing the cause of death in an investigation. These individuals work together in order to draw conclusions from evidence, primarily by applying their knowledge of the human skeleton to a case or subject at hand. The main focus of a Forensic Anthropologist is to process the crime scene, examine and process remains, create a biological profile, provide appropriate documentation of their findings, and testify in the court of law (Stanojevich, 2012). Their knowledge of the human body contributes to the outcome of a death investigation by providing law enforcement agencies with expert answers and conclusions, which ultimately aids in the outcome of any given case.

Summary: Human being has always been curious about its surrounding, fellow creatures, cosmology and no less about its own existence. This curiosity of man takes him to the roots of history, the cobwebs of polities, biology and plethora of other field of study. However, anthropology is an amalgamation rather says a beautiful patchwork of many branches of science and humanities. Thus, Forensic anthropology is the sub-branch of biological anthropology which uses the anthropological knowledge and application for medico-legal process. Forensic anthropology encompasses the field recovery of partly or completely skeletonised remains and their laboratory management and analysis. It involves the determination of whether the skeletal remains are of animal or human origin; the number of individuals represented; the race, sex, age and stature of the individuals concerned; the pathology, injuries and anomalies that are present; the identification of unique individual characteristics; the estimation of the time since death and manner and cause of death; and the investigation of the individual’s identity by matching of post-mortem skeletal evidence with ante-mortem records or portraits (Wood et al,2002). Forensic Anthropologists are helpful for the investigation of crime /crime scene because of their training in cultural anthropology, archaeology, taphonomy and biological anthropology. Their training in cultural anthropology allows them to identify cultural markers that define ethnic, religious or national groups. Their training in anthropology, archaeology and taphonomy gives them the skills needed to excavate clandestine graves and crime scenes where any incident occurred (Byers 2005). The main focus of a Forensic Anthropologist is to process the crime scene, examine and process remains, create a biological profile, provide appropriate documentation of their findings, and testify in the court of law (Stanojevich, 2012). Their knowledge of the human body contributes to the outcome of a death investigation by providing law enforcement agencies with expert answers and conclusions, which ultimately aids in the outcome of any given case.

ABFA, American Board of Forensic Anthropology American Board of Forensic Anthropology
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Investigating identification disparities in forensic anthropology casework

Roles Conceptualization, Formal analysis, Methodology, Project administration, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliations Department of Anthropology, University of Illinois at Champaign-Urbana, Urbana, Illinois, United States of America, Carl R. Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, Illinois, United States of America

Roles Formal analysis, Methodology, Visualization, Writing – original draft, Writing – review & editing

Affiliations Department of Health and Exercise Sciences, Truman State University, Kirksville, Missouri, United States of America, Forensic Science Program, George Mason University, Fairfax, Virginiai, United States of America

Affiliation Department of Anthropology, California State University Fresno, Fresno, California, United States of America

Roles Data curation, Writing – original draft, Writing – review & editing

Affiliation Forensic Anthropology Unit, University of North Texas Center for Human Identification, Fort Worth, Texas, United States of America

Affiliation Trace Evidence Unit, Laboratory Division, Federal Bureau of Investigation, Quantico, Virginia, United States of America

Roles Conceptualization, Writing – review & editing

Affiliation Anthropology and Sociology Department, Western Carolina University, Cullowhee, North Carolina, United States of America

Roles Writing – original draft, Writing – review & editing

Affiliation New York City Office of Chief Medical Examiner, New York City, New York, United States of America

Cris Hughes,
An-Di Yim,
Chelsey Juarez,
John Servello,
Richard Thomas,
Nicholas Passalacqua,
Angela Soler

Published: November 1, 2023
https://doi.org/10.1371/journal.pone.0290302
Reader Comments

Forensic anthropology is shifting to reflect on the impact of its practices within the criminal justice context in important ways. Here, we contribute to this essential work by examining how decedent demographics as well as estimations of biological profile components are related to identification trends in forensic anthropology cases. The study uses data from more than 1,200 identified and unidentified forensic anthropology cases from three agencies (together representing a nation-wide sample). We found the following: i) multivariate analyses indicated that decedent sex, age, and race and/or ethnicity are not related to case identification rates in the pooled United States sample, ii) when identification rate differences do occur, they appear to be smaller effects, more agency-specific, and/or related to the context of a particular agency, iii) for the agency-specific sample with available data, there was no consistent evidence for a discrepancy in the duration of an identification investigation based on a decedent’s sex, age, or race and/or ethnicity, iv) forensic anthropological estimations of sex, age, and ancestry can improve the odds of identification for decedents, although these are small effects, and v) reporting an ancestry estimation does not appear to impact decedent race representation among resolved unidentified person cases. Although previous studies have identified demographic discrepancies in other areas of the criminal justice system, the results presented here suggest that decedent demographic estimation practices by forensic anthropologists in general do not appear to be related to discrepancies in identification trends, but more research is needed to examine whether these findings hold. Contextual factors and practices specific to each investigative agency likely contribute to identification trends.

Citation: Hughes C, Yim A-D, Juarez C, Servello J, Thomas R, Passalacqua N, et al. (2023) Investigating identification disparities in forensic anthropology casework. PLoS ONE 18(11): e0290302. https://doi.org/10.1371/journal.pone.0290302

Editor: Roberto Scendoni, University of Macerata: Universita degli Studi di Macerata, ITALY

Received: February 15, 2023; Accepted: August 5, 2023; Published: November 1, 2023

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Data Availability: Regarding data sharing, deidentified data used in this study cannot be openly shared in the journal for legal reasons, as the underlying data is law enforcement-sensitive. Working with this data required permission from the three contributing forensic agencies. Data underlying the results presented here may be requested from the FBI ( https://www.fbi.gov/investigate/how-we-investigate/science-and-technology ; [email protected] ), UNT ( https://www.unthsc.edu/center-for-human-identification/ ; [email protected] ), and NYC OCME ( https://www.nyc.gov/site/ocme/index.page ; [email protected] ). Restrictions may apply to the availability of these data, please contact the respective agency to inquire.

Funding: The author(s) received no specific funding for this work.

Competing interests: authors Soler, Servello, and Thomas each work in an agency from which data was collected and analyzed for this study. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Introduction

With the National Academy of Science’s report, Strengthening Forensic Science in the United States : A Path Forward over a decade in the rearview mirror, research in forensic anthropology has consistently and robustly addressed measures for assessing the accuracy and reliability of approaches to forensic casework. While the standards laid out in that report will continue to inform methodological approaches and research in forensic anthropology for years to come, recent discussions and work in the discipline have highlighted the need to give equal consideration to researching the contextual impacts of the practice of forensic anthropology—in other words, discovering and coming to terms with both positive and deleterious downstream effects of forensic anthropology practice in the investigation context, as well as the broader social context.

In the summer of 2020, nationwide demands for radical change to the criminal justice system were ignited as a result of the high profile (but not isolated) incidents of a series of police killings of Black individuals in the United States. Within the discipline of forensic anthropology, researchers simultaneously called for the critical examination of ancestry estimation as it relates to concepts and applications of race in research and unidentified persons casework. Specifically, Bethard and DiGangi [ 1 ] asserted that the practice of ancestry estimation of unidentified human skeletal remains by forensic anthropologists is doing harm to communities of color by reifying racialized science, hindering identifications in casework, and applying methods with skeletal data for which we lack evolutionary understanding. In response, Stull and colleagues [ 2 ] countered that ancestry estimation plays a role in repatriation and determination of medicolegal significance and cautioned against abandoning ancestry estimation without consultation with both stakeholders and anthropologists in the discipline. While providing different viewpoints, both Bethard and DiGangi [ 1 ] and Stull et al. [ 2 ] did align regarding the need for data-driven research to investigate each others’ proposed perspectives. This conversation garnered national attention and laid the groundwork for recent critical discussions and research on issues of diversity and inclusion [ 3 – 6 ], the perception and framing of race and ancestry [ 7 – 12 ], as well as gender and biological sex [ 13 – 15 ], and reexamination and improvement of the language used in our research [ 16 , 17 ]. As forensic anthropology works to critically engage with concepts beyond the science itself and associated methodological approaches, it is essential to recognize that this discipline is part of the larger community of death investigation, for which similar conversations are rarely happening (with a few exceptions, see [ 18 , 19 ]), yet are equally necessary. Forensic anthropologists’ work at self-criticality has implications not only for our own practice, but also has the potential to impact and improve the practice of the greater medicolegal death investigation community [ 20 ].

One goal of forensic anthropological analyses in medicolegal death investigations is to produce information from an unidentified person’s skeletal remains that narrows down the pool of potential missing persons from which this person may have originated, thus producing an investigative lead that may assist in the successful identification of the person. Forensic anthropologists engage with socially-constructed concepts of race and ethnicity because these are employed as criteria used to narrow the pool of potential matches within the missing and unidentified person investigation context in the U.S. [ 2 , 21 ]. Furthermore, tracking decedent race and ethnicity allows researchers to provide insight into decedent trends. Recent studies have provided forensic anthropology with a clearer sense of the demographics of decedents common in forensic anthropology cases where the decedents were successfully identified [ 22 , 23 ]. Notably, research indicated that Black and Hispanic persons were disproportionately overrepresented in forensic anthropology casework when compared to U.S. census data population proportions. While insight into demographic representation is an important first step, it has been difficult to comprehensively track investigative trends that may produce and/or result in investigative outcome disparities (e.g. successful identification rates) across demographics for forensic anthropology casework. Researching investigative trends, strategies, hurdles, and biases—all of which may differ at an agency level and can influence the investigative success of an unidentified persons case—include myriad factors for which readily available, standardized data do not exist. However, given that these factors influence investigative outcomes (e.g. duration of an investigation to completion; successfully making an identification), exploring whether there are trends and/or disparities in these outcomes is a logical first step. Here, we explore such investigative outcomes within the context of decedent demographic factors of sex, age, and race/ethnicity, and the information provided by the forensic anthropologist, using available data on casework success and investigation duration. Specifically, this study addresses the following:

Aim 1. For forensic anthropology cases , do investigation trends (e . g . identification success rate; duration of an investigation) differ across demographic backgrounds (e . g . sex , age , race/ethnicity) ? Based on the extensive bias and structural violence and vulnerabilities documented in the criminal justice system and forensic investigations (discussed in depth below), we hypothesize that Black, Indigenous, and People of Color (BIPOC) cases may have lower success rates or longer investigative durations for identifying the skeletal remains as a missing person. In the present study, our first aim is to test this hypothesis using decedent demographic data from over 1,200 U.S. forensic anthropology cases of unidentified persons (both resolved and open).
Aim 2. Is the decedent information included in forensic anthropology reports (e . g ., estimations of decedent ancestry , sex , and age) related to the (de)prioritization of particular individuals over others in regard to identification efforts . This aim corresponds to the hypotheses proposed by Bethard and DiGangi [ 1 ] that information related to decedent race/ethnicity (e.g. forensic anthropologists’ ancestry estimations) of an unidentified person may provide grounds for “racial bias on the part of investigators” which “may hinder identification efforts.” Indeed, they propose that the very information provided by forensic anthropologists may be a driving factor for inadequate efforts by investigators to resolve cases of non-White decedents [ 1 ]. While data that directly correspond to prioritization by investigators are unavailable in the present study, proxy data are employed, including the duration of an investigation as well as success rates of identifications. Given that Bethard and DiGangi [ 1 ] hypothesize that investigations may be hindered when relevant demographic information is provided to investigators, investigative success and duration are proxies that represent the comprehensive investigation. Importantly, investigation hinderances and/or deprioritizations would be included in the factors influencing investigative success and duration, and if sufficient to influence the investigation would be observable in the present analysis. Bethard and DiGangi’s hypothesis is explored in several ways, using data on ancestry estimation availability, and when estimated, what those corresponded to in terms of race/ethnicity. The analysis was further expanded to include both age and sex estimations, to comprehensively explore how forensic anthropologists’ estimations of demographic data influence an investigation.
Aim 3 . Does providing information related to the decedent’s age , sex , and/or race/ethnicity influence the odds of an identification ? For this research aim, the hypothesis is based on Bethard and DiGangi [ 1 ], who challenge the assumption that ancestry estimations are critical for contributing to successful investigations of unidentified persons. We extend the testing of this assumption beyond ancestry estimations to include estimations of age and sex. We compare the identification rate for cases with and without these estimations.

Documenting decedent demographic and investigative trends in United States forensic casework allows for a better understanding of how institutional (i.e., United States Criminal Justice System) and societal factors may be related to, or directly affecting the time to identification and the overall success of identification for various populations within the United States. Thus, documenting demographic information and analyzing these data for trends can in turn have important implications for improving approaches to identification investigations [ 24 – 26 ].

It is worth noting that forensic anthropological analyses typically represent a small component of identification investigations, and demographic and investigative trends potentially vary depending on which aspect of the forensic setting one examines (e.g., all medicolegal death investigations versus forensic anthropology cases). However, the goal of this study is to explore whether there is a relationship between identification status of decedents who receive an anthropological analysis and demographic factors (including sex, age, and race and/or ethnicity) to infer whether any differences in case identifications exist at a regional and/or national scale.

Forensic anthropology’s discourse on ancestry estimation and race

The present focus on examining whether investigation and identification trends differ among decedent demographic groups stems from the much broader discourse within the discipline of forensic anthropology. The broader discourse was borne out of the initial work of Bethard and DiGangi [ 1 ], in which the authors called on the U.S. forensic anthropology community to stop conducting ancestry estimations in forensic anthropology casework for three main reasons. First, they insisted forensic anthropologists have not considered whether ancestry estimations might hinder identification efforts, related to the entrenched (conscious and unconscious) racial biases within the criminal justice system at large. That is, for example, unknown human remains whose ancestry estimation is consistent with the decedent’s race being Black or African American (but potentially extends to BIPOC individuals as a whole) may receive less investigative attention/prioritization than those decedents considered White. Secondly, the authors proposed a framework in which the practice of ancestry estimation reifies race as biology and perpetuates typological notions of race. Essentially, they argued that the act of ancestry estimation itself, the categorizing of humans based on phenotypes is in and of itself the “reliving” of a practice deeply imbedded in a racist history which supported not only slavery, the divestment of Native Peoples from their land, and Jim Crow, but is allowed to continue because of the lack of a reckoning with biological anthropology’s racialized past [ 27 , 28 ]. Thirdly, Bethard and DiGangi [ 1 ] demand a cessation to the use of macromorphoscopic traits in ancestry estimation without a full grasp of the heritability of these traits.

In response to the initial publication by Bethard and DiGangi (1), scholars and practitioners have begun to open up the conversations to an array of relevant findings. Adams and Pilloud (7) explored instances of misappropriation of psychology and biological anthropology research by white nationalists to justify their racist beliefs, and documented ways in which biological anthropology research was used to argue for the existence of racial typology and urged researchers to consider the broader implications of their research beyond their discipline and intended application. Other recent works [ 10 , 11 , 29 – 32 ] recommend moving towards a practice of estimating population affinity, which advances beyond continental allocations often associated with ancestry estimations, and incorporates a comprehensive understanding of population histories as well as ongoing dynamics (sociopolitical, economic) that can influence local patterns of biological variation. In turn, this approach considers how categories and terms used to describe the reference samples represent social meaning relevant to local communities [ 17 , 30 , 31 ]. Several studies propose that current methodological approaches and reference sample representation may be impacting the accuracy rates of ancestry estimation, and suggest that increasing diversity of reference samples would better serve the forensic anthropological casework demographics [ 22 , 23 ]. Furthermore, Go and colleagues [ 33 ] documented how those conducting ancestry-related research, as well as the skeletal samples used, are largely WEIRD (Western, educated, industrialized, rich, and democratic). The authors rightly pointed out that this lack of diversity among practitioners and samples reifies harm and “informs the history, values, and practices of forensic anthropology on a global scale” (Go et al., [ 33 ], p. 156).

Established demographic trends in U.S. investigations

The previously-reviewed body of work provides data points forensic anthropologists can use to inform their decision (both collectively and individually) of whether and how they will practice ancestry or population affinity estimation moving forward. The current study provides another “data point” for consideration in the larger ongoing conversation regarding the contextual impacts of our practice. Furthermore, this study intentionally expands the inquiries beyond ancestry estimation, to incorporate estimations of sex and age, as research has established that other demographic factors in addition to or in tandem with race/ethnicity are related to investigation and criminal justice disparities. Bethard and DiGangi [ 1 ] and DiGangi and Bethard [ 34 ] referenced sociological work on “missing White woman syndrome” as an example, which highlights how certain cases (those involving White women) are prioritized in social media and news outlets over others [ 35 ] and therefore have greater odds of resolution. Other studies have explored the extent to which BIPOC individuals and/or members of the LGBTQ+ community are negatively impacted by the criminal justice system in a variety of ways, from police engagements, to investigative outcomes, to sentencing and parole results [ 36 – 44 ]. Tallman et al. [ 15 ] surveyed 128 forensic anthropologists and found 28.9% had encountered transgender individuals as part of their casework and called for greater consideration of queer theory in forensic anthropology research and practice.

Within the medicolegal death investigation system, Goliath and Cosgriff-Hernandez [ 39 ] comprehensively reviewed racial disparities and biases, including the criminal justice system policies that have led to a disproportionate number of BIPOC individuals and adults coming from vulnerable circumstances represented in the system. Studies have suggested that investigations of missing Black individuals remain unresolved more often, and when resolutions do occur, take longer than cases involving White individuals [ 45 , 46 ]. This statistic is particularly concerning as we know that Black individuals make up a disproportionate number of missing and unidentified cases in the United States at 33%, yet only comprise approximately 13% of the United States’ population [ 47 ]. Related to this discrepancy, it has been argued that differential treatment of various demographic groups has ultimately influenced who is comfortable and/or willing to engage with law enforcement regarding investigations, including investigations of unidentified remains and missing persons [ 48 – 53 ].

Based on the works reviewed here, scientific investigation is warranted regarding whether demographic factors are related to identification status (identified or not) and the rate (i.e., death investigation duration) at which a case is resolved. If such disparities exist, the reasons can be multifactorial, such as investigative practices, practitioner choices, public participation and/or trust in investigations, and structural vulnerabilities. Collectively, the works cited above suggest that there is much more to understand regarding decedent demographic trends related to forensic anthropology practice. By studying the relationship of decedent demographics and identification trends for forensic anthropology casework, we can begin to understand the complex roles that forensic anthropologists’ estimation of a decedent’s biological profile (including sex, age, and ancestry) may have on the identification process. The results of this study can help inform practitioner strategies and policies for mitigating investigation biases.

Addressing analytical limitations: Data and interpretations.

It is important to note that if demographic differences in case identification trends are found in this study, it does not provide evidence for a direct correlation to overt prioritization of one case demographic over another; however, it would provide a foundation and direction for further study into what may be driving such differences. Concomitantly, if demographic differences in case identification trends are not found, it does not provide evidence that medicolegal death investigations are wholly unbiased. Because case investigations (and their success or failure) depend on myriad factors, this study is only a first step in exploring identification trends related to decedent demographics in United States forensic anthropology casework.

It is important to set expectations of studies with case datasets like this up front, and it is helpful to consider comparable roadblocks highlighted in criminal justice research. Knox and Mummolo [ 54 ] examined why research on whether and to what degree police behavior is racially biased was not as forthcoming and conclusive as one might hope, given the heightened attention by scholars in recent years. They emphasize that data constraints/limitations only allow the study of isolated aspects of police–civilian encounters, and thus do not fully represent the myriad of choices, interactions, standard operating procedures, and other factors related to case contexts. Indeed, the data being relied upon by researchers are largely generated by police for police administrative purposes, ultimately producing a fragmentary data source that can lead to incomplete and disparate results when analyzed, given that the original data-generation was not geared towards answering the kind of questions that are now in the forefront of many social scientists’ minds. Relating to the present study, we acknowledge that medicolegal death investigation data of forensic anthropology cases largely originates with the same purposes, for case management and tracking, and is bound by all of the nuanced choices of what to track (and what not to track) and how to track it. If disparities in identification trends exist, then it would be ideal to explore elements of an investigative context that could produce such disparities, such as identification modality, availability of missing person reports/antemortem records/family reference DNA samples, and the quality of evidentiary data, and more. Here, we initiate the work for establishing whether investigative disparities for forensic anthropology cases exist, but the exhaustive factors that may be producing disparities are not readily available in this study. For this initial study, we focus on decedent sex, age, race, as well as agency, case year, and geographic location.

Materials and methods

The forensic anthropology unidentified persons cases used in this study were drawn from three agencies’ databases: the Federal Bureau of Investigation Laboratory, the New York City Office of Chief Medical Examiner (NYC OCME), and the University of North Texas Center for Human Identification (UNTCHI) Forensic Anthropology Unit (FAU). Table 1 provides data for the three agencies regarding sample sizes, the case year ranges, and the percent of individuals identified in each agency sample. Both resolved (i.e. person is identified) and unresolved (i.e. persons’ remains unidentified to date) cases were included. Below is a brief description of any additional considerations for each agency dataset. To provide consistency in casework across the three agencies, cases were included in the sample if they met all of the following criteria: the remains were decomposed beyond the fresh stages, estimation of the biological profile was completed, no tentative, presumed, or positive identification was known upon case intake, and cases were determined to be of medicolegal significance. Tentative identification data were inferred from the case investigation notes or directly reported from the investigating agency. For resolved cases, many had comprehensive information on the individuals’ demographic data for sex, age, and race and/or ethnicity, however some were missing information which is why the sample sizes vary per analysis performed.

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https://doi.org/10.1371/journal.pone.0290302.t001

FBI case dataset.

The Federal Bureau of Investigation (FBI) Laboratory performs a broad range of forensic examinations on skeletal remains and maintains detailed files for a large number of resolved and unresolved unidentified decedent cases submitted by jurisdictions nationwide. These case files often contain an anthropological biological profile assessment, including estimates of age, sex, ancestry and stature. For those cases with successful positive identification of the decedents via DNA analysis or other investigative means, the biological profile characteristics of the decedents are known and documented. These cases contain anthropological examinations conducted both by anthropologists at the FBI Laboratory and outside of the FBI Laboratory, providing a variety of analyses and data sources. Overall, 525 cases (with most anthropological examinations dating from 2000 or later) were selected. In general, cases with older anthropological examinations were submitted to the Laboratory for DNA analysis, which was not available at the time of recovery, or for facial approximation as part of cold case initiatives carried out by local medicolegal authorities. Reported sample variables used in the present study include: case recovery and analysis years; case identification status (identified or not identified); forensic anthropological estimates of sex, age, and ancestry for the decedents; known decedent demographic data (sex, age, race); and the National Missing and Unidentified System’s (NamUs) region code for case origin. Of note for this study, a key feature of the FBI dataset is that the vast majority of the forensic anthropology cases were investigated by an outside agency with jurisdiction over the case, not the FBI. Therefore, the FBI’s involvement in these cases is limited to the services requested from the FBI Laboratory by the outside agency and does not include ongoing investigation of these cases. In this study we will refer to the FBI agency dataset, but it is necessary to recognize that the FBI’s dataset represents cases worked by forensic anthropologists from an array of agencies and that the FBI does not have jurisdiction over these cases.

NYC case dataset.

This portion of the study dataset is comprised of resolved and unresolved cases (n = 368) from the New York City Office of Chief Medical Examiner (NYC OCME). For those cases with positive identification of the remains, the biological profile characteristics of the decedents are known and documented. These cases span several decades, with the majority of cases with forensic anthropological analyses carried out from 2004 onward, but some of the cases prior to this have been retroactively examined by forensic anthropologists at the agency. The majority of cases in this sample are from the New York City jurisdiction, but some are from other agencies in the surrounding areas within New York State. Thus, the originating agency for the majority of the NYC dataset is the same as the agency performing the forensic analysis and investigation of the cases, which is very different from the situations described for UNT and FBI. Reported sample variables used in the present study included: case recovery and analysis years; case identification status (identified or not identified); forensic anthropological estimates of sex, age, and ancestry for the decedents; known decedent demographic data (sex, age, race); and the NamUs region code for case origin.

UNT case dataset.

This portion of the study dataset consists of resolved and unresolved cases (n = 361) examined at the University of North Texas Center for Human Identification (UNTCHI) Forensic Anthropology Unit (FAU) from 2008 to 2020. Remains examined at the FAU were submitted by investigative agencies nationwide. Cases were recovered between 1960 and 2020, the majority of which were found between 2012–2018. For those cases with positive identification of the remains via DNA analysis or other investigative means, the biological profile characteristics of the decedents are known and documented. Additionally, cases with positive molecular associations (i.e., “DNA identifications”) were coded for presence/absence of available reference profiles (Family Reference Samples or CODIS-Convicted Offender Index). Reported sample variables used in the present study included: case recovery and analysis years; case identification status (identified or not identified); identification year; forensic anthropological estimates of sex, age, and ancestry for the decedents; known decedent demographic data (sex, age, race); and the NamUs region code for case origin. A key feature of the UNT dataset is that it does not have jurisdiction over the cases they examine because they are from other investigative agencies that are outsourcing the forensic anthropology analysis to UNT. Thus, UNT’s involvement in these cases is limited to the services requested by the originating entity and is not directly involved in the ongoing investigation of these cases. In this study we will refer to the UNT agency dataset, but it is necessary to recognize that UNT’s dataset represents cases worked by forensic anthropologists at UNT, however UNT is not the originating agency for any of these cases.

Case data standardization.

In the dataset, there is both known and estimated demographic information about the decedents. Known demographic information is derived from resolved cases when the decedent is positively identified, and includes sex, age and race/ethnicity often derived from legal or medical documentation/records. Not all resolved cases (i.e. identified cases) contain sex, age and race/ethnicity information, as these may not be known or available to the agency at the time of case resolution. Estimated demographic information is derived from the forensic anthropological analysis of the skeletal remains, and includes the estimation of biological sex, age, and ancestry. Not all resolved or unresolved cases have estimated demographic data, due to limitations with the analyses such as damaged or missing skeletal elements used by forensic anthropologists for these estimations. Both known and estimated demographic data are used separately or in conjunction as appropriate per study analysis. These are described in detail in the Supporting Information.

All but multivariate analyses were performed using JMP ® Pro 16.1.0. Multivariate modeling fitting was performed using the ‘lme4’ package [ 55 ] in the R Programming Language 4.1.0 [ 56 ]. Initial univariate comparisons of the forensic anthropology caseloads from the three agencies (UNT, FBI, NYC) were completed, including a comparison of the NamUs region of origin and the decedent demographic data distributions for each agency (sex, age, and race and/or ethnicity). Chi-square tests for agency distribution differences were carried out to compare the three samples. Identification status (identified or not identified) trends were then generated and compared across decedent demographic variables, and Chi-square tests (or Fisher’s Exact test when appropriate) and correspondence analyses were completed to compare the demographic distributions of identified versus unidentified individuals. We also examined the availability of biological profile information as it relates to identification rates.

Wilcoxon Rank Sum/Kruskal Wallis tests were used to infer whether there were significant differences in investigation duration (length of time to identification in years) across decedent demographic groups. This analysis requires an identified case sample and was completed using the UNT sample because both recovery date (by year) and identification date (by year) were only available from this agency. For the UNT identified case sample, the “investigation duration” was determined to be the total number of years from case recovery to identification.

Importantly, the analyses of investigation duration would inevitably include cold cases from many decades ago, and the prevalence of such cases will be dependent on the trends in U.S. demographics over the years, which could bias the sample if left unchecked and produce substantially different mean investigation durations. For example, while there are substantial cases in our dataset representing White decedents from 20 to 50 years ago, the majority of cases representing Hispanic decedents occur in more recent decades. As another example, improvements to investigations in more recent decades could produce shorter investigative durations. In order to mitigate the effects of these factors on identification duration, we took the following steps. For the identified case analysis of the relationship between investigation duration and decedent race, only Hispanic and White had sufficient sample sizes for comparison. Based on the case recovery year distributions, we found that Hispanic decedent cases became more prevalent in the UNT sample more recently, especially over the past decades, with the 90% (10% quantile) of all UNT Hispanic cases occurring in or after 2012, and the 75% (25% quantile) occurring in or after 2014. These were therefore used as the case year cutoffs in order to ensure comparable year distributions and prevalence for the White and Hispanic decedents. Furthermore, this time period allows for comparable identification modalities, as all cases are included in the period when UNT had DNA analyses regularly integrated into casework.

Mixed effects logistic regressions were employed to examine i) combinations of sex, age, and race and/or ethnicity as they relate to identification status, and ii) whether having estimates of biological profile components influences identification status. A mixed effects model taking into account the non-independence in the dataset was employed. In this case, we assume there are agency-specific identification trends (with regards to demographic factors) in addition to general trends in identification. That is, cases from one agency were handled by a particular group of practitioners with agency-specific training and experience and may be subject to the same influences. It is therefore necessary to explore agency-specific trends using a multivariate approach. Identification status was modeled as a binary outcome variable (identified vs. unidentified) while sex, age, race and/or ethnicity, and whether these components were estimated were modeled as categorical predictor variables. To ensure a fully represented data matrix, the combined demographic categories with zero cases were removed prior to model fitting. Since doing so removed all Juvenile individuals and all Native American individuals, we report both univariate and multivariate analyses results as they complement one another and provide a more comprehensive picture of the identification trends. The resulting model was then checked for collinearity between predictors as well as influential cases to ensure model assumptions are met [ 57 ]. To minimize abstraction, we describe our models in terms of comparison with the reference categories for the predictors. The reference categories are females, adolescents, and White.

Because multiple tests were performed on the same subsamples of the dataset, we used the Benjamini-Hochberg false discovery rate p- value adjustment for multiple tests [ 58 ]. To measure the effect size of the Chi-square tests, Cramer’s V was employed, using the 95% confidence interval for its estimated value. Cramer’s V is an extension of the correlation coefficient used for 2 x 2 contingency tables and ranges from zero to one, with zero implying no correlation (i.e., negligible effects) and values closer to one implying a strong correlation (i.e., large effects). Cramer’s V values can be interpreted using Cohen’s d degrees of freedom-informed approach [ 59 ]. While effect size is not traditionally used in forensic anthropology research, it has been considered a statistical best practice in many fields, including psychology, medicine, ecology and evolutionary biology [ 60 ]. However, the thresholds for interpreting what size effect is considered important is known to be relatively arbitrary unless there are other studies to compare it to. When comparative effect sizes are unavailable in the discipline, Cohen [ 59 ] proposed general thresholds for use: negligible effects ( V ≤ 0.10), small effects (0.10 < V < 0.30), medium effects (0.30 < V < 0.50), and large effects ( V ≥ 0.50). For this study, the thresholds are defined using the ranges provided above. We report effect size for three reasons. First, given the large sample sizes used in this study, the odds of statistically significant tests at p = 0.05 are extremely high, but not meaningful beyond that a relationship exists (slim chance of a Type I error), but the magnitude of the relationship between the variables of interest cannot be directly inferred from the p- value [ 61 , 62 ]. Thus secondly, reporting effect sizes for each of our analyses in the present study allows us to compare the strength of the relationships for each test and across agencies. Third, the effect sizes reported here can be used as the first comparison for future studies using effect sizes in our discipline when studying similar topics.

Comparing agency datasets: Demographics, geographic distributions, and identification rates

The three agencies have substantial differences in their regional representation ( Table 2 ), with the FBI sample being the most representative of the nine NamUs regions. The UNT sample is primarily represented by Region 4 (73% of its forensic anthropology caseload), but does have cases from all but Regions 8 and 9. In contrast, 100% of the NYC sample is from Region 6, the majority from New York City. When all three agency samples are combined, all NamUs regions are represented, although not evenly (e.g., Regions 4 and 6 comprise 54% of the total sample).

Region 1 (AZ, CO, HI, NM, NV, UT, Guam, Saipan), Region 2 (AK, ID, MN, MT, ND, OR, SD, WA, WY), Region 3 (IA, IL, IN, KS, MO, NE, OH, WI), Region 4 (AR, LA, OK, TX), Region 5 (AL, KY, MS, PA, TN, WV), Region 6 (CT, MA, ME, MI, NH, NY, RI, VT), Region 7 (FL, GA, NC, SC, Puerto Rico, US Virgin Islands), Region 8 (DE, MD, NJ, VA, District of Columbia), Region 9 (CA).

https://doi.org/10.1371/journal.pone.0290302.t002

Comparisons of the distributions for decedent sex, age, and race and/or ethnicity are presented in Table 3 . Regarding decedent sex, all agencies had at least twice the frequency of male decedents compared to female decedents. The FBI and NYC samples had comparable proportions, while UNT presented a slightly greater proportion of male decedents compared with the other two agencies. Age trends indicated that the UNT sample more frequently included young adults and less frequently included older adults compared to the NYC and FBI samples. When considering the combined frequencies of the three agency samples, juvenile and adolescent cases were the least common, while young adults and middle-aged adults were comparable in frequency. The greatest frequency differences in decedent demographic trends among the three agencies were for decedent race and/or ethnicity. The majority of UNT’s sample was comprised of Hispanic (55%) decedents, followed by White (17%) decedents. In contrast, the majority of NYC’s forensic anthropology sample was comprised of White (35%) and Black (25%) decedents. The majority of FBI’s sample was comprised of White individuals (43%), which were about two to three times as common as any other decedent race and/or ethnicity. For all agencies, Native American decedents and Asian decedents were the least frequent (0 to 5%).

https://doi.org/10.1371/journal.pone.0290302.t003

Chi-square tests of agency-specific differences for the frequency distributions of decedent sex, age, and race and/or ethnicity were performed, excluding those cases with an inconclusive decedent sex, age, or race and/or ethnicity. Furthermore, the Native American subsample was excluded from the Chi-square test for race and/or ethnicity because the sample sizes were not substantial enough and left some cells with zero cases. All tests for agency differences in decedent sex, age, and race and/or ethnicity frequencies yielded statistically significantly results ( Table 4 ). The accompanying Cramer’s V statistics indicated that decedent sex and age variation have a limited relationship (i.e., small effect) with agency of origin, while race and/or ethnicity variation appears to be more strongly related to agency of origin, with a medium effect.

Shaded cells indicate statistical significance of test for the adjusted p values.

https://doi.org/10.1371/journal.pone.0290302.t004

We compared the identification rates among the three agency samples ( Table 3 ) and found that identification rates ranged from 41% to 57%, with NYC identification rates being the greatest. The Chi-Square test for frequency differences in identification rates among the three agencies was a significant ( Table 4 ), but small effect. When pooled, the identification rate for the sample was 47%.

Aim 1: For forensic anthropology cases, do investigation trends (e.g. identification success rate; duration of an investigation) differ across demographic backgrounds

Pooled sample univariate analyses..

Using the pooled sample, we then explored the relationship between identification status (either identified or not identified at the time this data was collected) and its associated decedent demographic data (sex, age, and race and/or ethnicity). Cases where inferred decedent data for sex, age, or race and/or ethnicity were lacking were excluded from each analysis. The pooled samples’ Chi-square results for examining identification rate trends across decedent demographics are presented in Table 5 , and the identification frequencies associated with demographic data are presented in Fig 1 . Chi-Square tests and Cramer’s V were employed to identify any statistically significant and notable trends. The pooled sample’s results suggest that identification frequencies statistically differed with decedent age and sex, but not decedent race and/or ethnicity. The Cramer’s V measure of effects for age and sex effects on identification status are small and negligible, respectively, thus indicating limited differences among the age and sex subsamples’ identification rates. For sex, females (54% identification rate) were more frequently identified than males (47% identification rate). Fig 1 also highlights that the main frequency differences for age indicate that juvenile, adolescent, and older adult subsamples have higher rates of identification when compared with middle and young adult subsamples.

https://doi.org/10.1371/journal.pone.0290302.g001

Pooled and agency-specific tests performed. Shaded cells indicate significance of adjusted p -value.

https://doi.org/10.1371/journal.pone.0290302.t005

Agency-specific analyses.

Because pooling the sample could be masking agency specific trends, we again examined the relationship between identification rates and decedent demographic data (sex, age, and race and/or ethnicity) per agency sample. The identification rates per agency are reported in Fig 2 , and the Chi-square results are presented in Table 5 . We found that none of the three agencies yielded significantly different identification rates for males and females. For decedent age, we found that only the FBI sample’s identification rates significantly differed among age subsamples. While there were no significant differences in identification rates among age subsamples for UNT and NYC, their trends indicate agreement among the agencies in regard to identification rates, with Older Adult subsample having the greatest identification rates (74% and 72%, respectively). For the FBI and NYC samples, the Adolescent case subsamples had some of the highest identification rates (64% and 69%, respectively). The Middle Adult subsample exhibited the lowest identification rate for the FBI (47%) and NYC (51%) samples, and the second lowest for the UNT (49%) sample.

https://doi.org/10.1371/journal.pone.0290302.g002

When examining the relationship of decedent race and/or ethnicity with case identification rates, agency-specific datasets did not adequately represent all available subsamples used in the pooled sample. For NYC, Native American decedents were excluded, and for UNT Native American and Asian decedents were excluded. The FBI dataset had no groups excluded. The only agency with statistically significant differences in identification rates across race and/or ethnicity was the UNT sample ( Table 5 ), with a medium effect size. For the three groups examined (Black, Hispanic, and White), White decedents’ identification rate (81%) was twice that of Hispanic decedents’ (42%), while the Black decedent identification rate was intermediate (67%). In contrast, NYC Hispanic decedents present the greatest identification rate (81%) compared to Asian (61%), Black (69%) and White (66%) decedent identification rates. The FBI analysis had highly comparable identification rates for Black, Hispanic and White decedents (47–51%), while Native American and Asian identification rates were the greatest (63%) and lowest (21%), respectively. Given that the only agency with significantly different identification rates among race and ethnicities is the UNT sample, this suggests that the statistical significance of this same test when using the pooled sample is likely driven by the differences found within UNT, and not a nation-wide trend of lower identification rates for Hispanic decedents. It should be noted that the small samples for decedents—namely, FBI Asian (n = 14), FBI Native American (n = 16), and UNT Black (n = 15)—may not be representative of United States identification trends at large for these subsamples, and more data will be needed to better gauge the identification trends.

Pooled multivariate analyses.

While the univariate tests indicate trends for the independent factors of decedent sex, age, and race and/or ethnicity, it is also important to ensure that we take into account the multivariate nature of demographic data, as individuals simultaneously belonging to a specific combination of sex, age, and race and/or ethnicity for any given case, as well as considering agency of origin. This approach most strongly corresponds with the reality of casework, in that a decedent’s sex, age, and race and/or ethnicity would typically be simultaneously considered in a case and investigated within a particular agency. Thus, we employ a multivariate approach to more realistically infer the relationship between identification rates and decedent demographics. The multiple logistic regression model indicated the overall effects of decedent sex, age, and race and/or ethnicity were not significant, after agency effects were taken into account ( Table 6 ). The results of the logistic regression model also revealed the direction of identification rate differences while taking all demographic factors into account, and the results were consistent with the univariate findings. All other factors equal, females are more likely to be identified than males, Middle Adults are less likely to be identified than other age groups, and White and Asian decedents are more likely to be identified than other race and/or ethnicity. However, the amount of overlap in conditional probabilities among different categories for each individual predictor variable (sex, age, and race and/or ethnicity) again suggest the differences in identification rates among the subsamples are almost nonexistent for sex and race and/or ethnicity, and small for age, primarily driven by the Middle Adult group’s lower identification rates deviating from all other age groups. The model also allows us to explore the combination of factors such as sex and race and/or ethnicity as they relate to identification status ( Fig 3 ). Regardless of age, White females and Asian females have slightly higher probabilities of identification compared to other subsamples. However, the amount of overlap among subsamples is big and suggests that the effects of demographic factors to identification status, if any, are small.

Note the overlaps among subsamples suggest the effects of demographic factors on identification probabilities are small.

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The reference categories (odds ratio = 1) are female, adolescent, and White.

https://doi.org/10.1371/journal.pone.0290302.t006

Investigative duration trends.

To explore whether duration of an investigation differed across decedent demographics, we examined the relationship between investigation duration and decedent sex, age, or race and/or ethnicity using the UNT identified case sample ( Table 7 ). Employing Wilcoxon Rank Sum/Kruskal Wallis tests, we then tested for differences in the investigation duration distribution across decedent sex, age, and race and/or ethnicity. Subsamples analyzed for these analyses were limited to those with n ≥ 20, resulting in the following groups per decedent demographic component for the identified UNT case sample: decedent sex (Male and Female), decedent age (Young Adult, Middle Adult, Older Adult), and decedent race and/or ethnicity (Hispanic and White). Ninety-eight percent of the cases used in this analysis were DNA identifications, meaning that when holding identification modality constant, we can explore the effects of demographics on investigation duration. It has been hypothesized [ 1 , 34 ] that anthropological estimations of sex, age, or ancestry could influence investigations such that some demographics’ cases are prioritized over others resulting in lengthier investigation times for deprioritized groups. Therefore, in Table 7 we also report the percent of cases with corresponding biological profile estimation information available in the UNT samples analyzed for investigation duration trends. The vast majority of cases had their biological profile information available at some point in the investigation, and therefore it can be assumed that if this information was to bias the investigation in some way, we would see that emerge as differences in the investigation duration trends. The median investigative duration for all seven groups was one year, and the distributions of the investigative durations did not significantly differ among the tested sexes nor among the tested age groups. Regarding the race and ethnicity, recall from the Methods section that for the comparisons of Hispanic and White decedent investigation durations we employed for two case year cutoffs, 2012 and 2014. The 2012 analysis resulted in significantly different investigation duration distributions (but identical medians at 1 year), primarily in the upper quantiles (75%-100%) of the distribution, with Hispanic decedents having greater investigative durations than White decedents (2–5 years versus 1–3 years). In contrast, the 2014 analysis did not find significant differences in investigation durations for White and Hispanic decedents.

Shaded cells indicate significance of adjusted p -value.

https://doi.org/10.1371/journal.pone.0290302.t007

Aim 2. Is the decedent information included in forensic anthropology reports (e.g., estimations of decedent ancestry, sex, and age) related to the (de)prioritization of particular individuals over others in regard to identification efforts

Decedent demographic trends are analyzed similar to Aim 1, but with the dataset comprised of only forensic anthropology estimated demographic data. In this way, we are able to compare how forensic anthropologists’ estimated demographic information about a decedent are related to investigative trends. The identification trends for only estimated decedent sex, age, and ancestry were generally comparable to those found in Aim 1 using known and estimated decedent data, with a few exceptions highlighting greater demographic discrepancies. In particular, for the pooled agencies analyses, all three demographic factors (estimated sex, age, and ancestry) yielded significant differences in identification success rates (S1 Table in S1 File ), although the Cramer’s V effect sizes were negligible for estimated sex and small for estimated age and ancestry. Decedents estimated as White and Black had the greatest investigative success with 54% and 53% of cases identified, respectively. Clustered with lower investigation success rates (39%-41%) are decedents estimated to be Asian, Hispanic, or multiple labels. Agency-specific analyses of estimated demographic data and identification rates indicated no significant relationships for the FBI sample. For NYC, there was a significant relationship (small effect) between identification rate and estimated ancestry such that decedents identified as Multiple labels were less frequently identified. For UNT, both estimated age (small effect) and ancestry (medium effect) were significantly related to identification rate, with Young Adult decedents as well as Hispanic decedents less frequently identified than other groups. Agency-specific investigation duration trend analyses indicated no significant differences in time to identification for the included UNT sample (S2 Table in S1 File ).

The multivariate results, which allow for the composite demographic estimates to be observed are somewhat different from the results of univariate analyses, showing the overall effects of estimated sex, age, and ancestry were not significant, after agency effects were taken into account (S3 Table in S1 File ). This is consistent with the multivariate results for Aim 1. For the combination of estimated sex and ancestry and how they relate to identification status (S1 Fig in S1 File ), the 95% confidence intervals for the probabilities of identification all overlap. The wide identification probability CIs associated with decedents estimated to be Asian females and females with multiple ancestry labels are likely associated with their small sample sizes, and thus the lower probabilities of identification need further investigation with more robust samples. For the other six group, White and Black males and females have substantial overlap in their 95% CIs for identification probability, while Hispanic males appear to be the lowest and have limited overlap with the White males. This trend is consistent with odds ratio analyses (S3 Table in S1 File ), where the only statistically significant odd ratios was White decedents being twice as likely to be identified as Hispanic decedents.

Aim 3. Does providing information related to the decedent’s age, sex, and race impact the odds of an identification?

We examined whether biological profile estimates provided by the forensic anthropologist (e.g., sex, age, or ancestry) have a relationship with identification rates. We performed a mixed effects logistic regression to infer whether identification rates related to whether or not forensic anthropology decedent demographic estimates were provided (e.g. “provided” or “not provided”), taking case agency into account. The odds ratios for the presence of biological profile components are as follows: 2.16 (95% confidence interval: 0.72–6.44, p > 0.05) for sex, 1.21 (0.47–3.15, p > 0.05) for age, and 1.05 (0.47–2.34, p > 0.05) for ancestry) indicated that estimations of each biological profile component only had a limited relationship with the probability of identification. When all three components were estimated (compared to when no component was estimated), the probability of identification increased twofold ( Fig 4 ).

An increase in identification probability is evident when all biological profile components are estimated (26.7% probability of identification with no biological profile component estimated vs. 50.1% probability of identification with all biological profile components estimated).

https://doi.org/10.1371/journal.pone.0290302.g004

To better understand which agencies are contributing to the observed differences in identification rates in the multivariate models, we examined the relationship between identification status and the presence or absence of forensic anthropology estimates of sex, age or ancestry for the agency-specific samples using univariate tests ( Table 8 ). We found that NYC identification rates significantly improved when sex, age, or ancestry estimations were provided by 40%, 27% and 25%, respectively, compared to when these estimations were not provided, but all were considered small effects. In contrast, the FBI and UNT presented no significant differences in identification rates related to the presence or absence of sex, age, or ancestry estimations.

The "n/a" status for the UNT age test is because age was estimated in all cases and thus the test could not be performed. Shaded cells indicate statistical significance of test for the adjusted p values.

https://doi.org/10.1371/journal.pone.0290302.t008

We performed a follow-up analysis which explored whether having an ancestry estimation available (two levels: ancestry estimation provided; ancestry estimation not provided) differentially impacted the identification outcome across decedent race and/or ethnicity. This analysis was performed to explore whether trends exist that suggest cases are (de)prioritized by the ancestry information that the forensic anthropologist provides. For example, if unidentified persons investigations are biased towards prioritizing cases of White decedents, then we would expect to see a greater proportion of White decedents in the sample of positively identified cases with ancestry estimations, compared to the positively identified case sample without ancestry estimations. Therefore, we analyzed whether the proportion of race and/or ethnicity groups differed between identified individuals with ancestry estimations versus identified individuals without ancestry estimations. In this scenario, the subsample of identified case without an ancestry estimation is considered the control sample, as there is no information on the decedent’s possible race and/or ethnicity to potentially bias the investigation, and thus the proportions of race and/or ethnicities in this subsample will be considered the control. Alternatively, the identified case sample with ancestry estimations can be considered the biased case subsample, as there is information on the decedent’s possible race and/or ethnicity, which has the potential to bias the investigation.

For this analysis, identified individuals representing three decedent races and/or ethnicities (those with substantial sample sizes being Black, White, and Hispanic decedents) from all agencies were used. We found that race and/or ethnicity proportions of identified cases ( Fig 5 ) were not significantly related to whether or not an ancestry estimation was reported ( N = 522, adjusted p = 0.066; Cramer’s V = 0.106). While not significant, it is interesting to note the trends observed, with both Black and Hispanic decedents exhibiting higher proportions (9% and 6% higher, respectively) in the identified case subsample when ancestry was estimated, while White decedents had a concomitant decrease (14% decrease). Similar to the trends of the pooled sample, the agency specific analyses showed an increase in the identification of Black decedents when ancestry is reported. However, only UNT exhibits significant differences between Black, Hispanic and White decedent proportions for identified individuals with versus without an ancestry estimation (Fisher’s Exact Test, N = 143, p = 0.028 Cramer’s V = 0.225). For UNT, the identification of Hispanic individuals almost doubles (to 63%) when ancestry information is reported, compared with White decedents whose frequency is almost halved (30%).

https://doi.org/10.1371/journal.pone.0290302.g005

Similar analyses could not be performed for decedent sex or age because there are only a limited number of identified decedents without forensic anthropology estimates of age or sex, and thus inadequate comparative data of identified decedents with or without this biological profile information. An unreported biological profile estimation may be due to several factors, including but not limited to incomplete and/or damaged skeletal material, methodological outcomes with weak probabilities, or contradicting outcomes from various methods.

This study examines the broader context of identification trends for forensic anthropology casework, as it relates both to decedent demographics and the information provided by the forensic anthropologist (the biological profile estimations). We examined these trends for both pooled and agency-specific samples because agency contexts (e.g., jurisdiction of cases, decedent demographics of casework) significantly differ among the three datasets included in the present study.

Do identification trends vary across decedent demographics?

In Aim 1, we examined the relationship between identification rates and decedent demographics (known and estimated) using both univariate and multivariate approaches. The multivariate logistic regression offered the most comprehensive analysis in that it allowed for the simultaneous consideration of sex, age, and race and/or ethnicity of each decedent as well as the agency effects. The model indicated the overall effects of decedent sex, age, and race and/or ethnicity on identification rate were not significant ( Table 6 ). These findings corroborate the univariate analyses of the pooled sample, which indicated that while both decedent age and sex significantly related to identification rate, their overall effects on identification rate were small or negligible, and appear to become insignificant when considered in tandem with other relevant factors in the multiple logistic regression. When comparing to the agency-specific univariate tests where the only significant finding was a relationship between identification rate and decedent race and/or ethnicity for UNT, this factor did not remain significant in the multiple logistic regression when agency differences were taken into account. These Aim 1 analyses suggest that decedent sex, age, and race and/or ethnicity have a limited (univariate analyses) to negligible (multivariate analysis), relationship with identification rates for the study samples.

Beyond identification rate, duration of the investigation for resolved cases was examined in Aim 1. The significant increase in investigation duration for UNT cases from 2012 to present for Hispanic decedents compared to White decedents compared to the lack of significantly different investigation durations for Hispanic and White decedents by 2014 may be explained by the changes of undocumented migration patterns around this time. Deaths of undocumented migrants in Texas were substantially increasing around this time, surpassing Arizona’s numbers in 2012 [ 63 ]. The influx of undocumented migrant deaths could have impacted UNT’s caseload, with needed investigative adjustments to accommodate the rise in this decedent demographic. By 2014 (through 2021), we found that the investigation durations were no longer elevated for Hispanic decedents (compared to White decedents), which could correspond with the sustained uptake of investigative strategies by the agencies served by UNT and the UNT Forensic Anthropology Unit itself. Interestingly, even though UNT’s Hispanic and White decedents exhibited the most significant difference in identification rates , in more recent years (2014 to present) when investigations do yield an identification, Hispanic and White decedents do not appear to significantly differ in the amount of time it takes to make those identifications. Furthermore, comparable investigation durations across subsamples cannot be explained by cases that come in with tentative identifications nor the modality of the identification, as those were controlled for. For future studies, examining this variable using a finer scale, such as months instead of years, and with a larger data set from more agencies would be ideal to corroborate the trends found with the available UNT data.

Do identification trends vary across estimated decedent demographics?

Aim 2 performed similar analyses to Aim 1, but with a sample whose decedent information was entirely based on the forensic anthropology biological profile estimates. In this way, Aim 2 explicitly examined the relationship of identification trends with the estimated decedent demographics data, which are what investigators would have been privy to during their investigations. Recall that it is this estimated demographic information that Bethard and DiGangi [ 1 ] proposed could influence the way in which an investigator (de)prioritizes one case over another. In general Aim 2’s univariate trends were similar to the Aim 1, with small to negligible effects for most estimated decedent demographics, and with a medium effect for estimated ancestry. Aim 2’s multivariate analysis of identification rates across various estimated decedent demographics indicated that only ancestry was influential, but the only statistically significant odds ratio for being identified (S3 Table, S1 Fig in S1 File ) was for decedents estimated as Hispanic versus White at 0.44. This finding is consistent with the univariate results for Aims 1 and 2 where White decedents were identified at twice the rate as Hispanic decedents for UNT cases. While not significant, the FBI’s analysis also indicated that Hispanic decedents had the lowest rate of identification among those analyzed. However, agency variation is important to acknowledge, as Hispanic decedents had the highest identification rates in NYC at 75%, which was the greatest identification rate for any decedent ancestry, race, and/ethnicity examined. Furthermore, similar to Aim 1, even within an agency with a low rate of identification of Hispanic cases like UNT, Aim 2’s analysis of investigation duration did not result in statistically significant differences for the three compared groups (S2 Table in S1 File ). Collectively, Aim 2 exhibited more statistically significant differences in identification rates than Aim 1, suggesting that the particular information provided by forensic anthropologists has a relationship with identification outcomes.

Does the availability of biological profile estimations relate to identification trends in forensic anthropology cases?

We also addressed the question of identification discrepancies when biological profile estimates are provided to investigators. Through univariate and multivariate testing, we found that identification rates appear to have a significant but limited relationship with the availability (e.g. presence or absence of this information) of biological profile estimations. Trends from the pooled sample’s multiple logistic regression indicate that decedents with all three biological profile components present in a case report have a greater probability (50%) of being identified compared to decedents who have none of these biological profile components estimated (27%). Agency-specific univariate analyses yielded further insight ( Table 8 ), highlighting that NYC was the only agency where the presence of sex, age, and ancestry estimations each independently significantly improved identification rates by 40%, 27% and 25%, respectively.

The relationship between forensic anthropological analyses/involvement with a case and identification rates can also be considered within the nationwide context of identification rates. The pooled FBI, NYC, and UNT identification rate (47%) is almost double the rate of identifications of unknown individuals uploaded to NamUs. Out of the 18,740 unidentified individuals uploaded, approximately 27% have since been identified (data accessed on 7/28/2021). Interestingly, cases of unidentified individuals uploaded to NamUs also include individuals with a tentative name upon the initiation of the investigation which presumably have a better chance of being identified than those without a lead. However, individuals with a tentative name were excluded from the present study, which indicates that the identification rates reported here are likely an underrepresentation of the overall identification rates for U.S. forensic anthropology cases.

One key difference between NamUs and the present study is that NamUs includes all cases of unidentified individuals, while the present study only includes unidentified individuals with a forensic anthropological biological profile (though not necessarily complete). Any discrepancy in overall identification rates between NamUs and the present study could also be tangentially related to the agencies’ represented in the two datasets—specifically, that agencies that hire in-house forensic anthropologists are inherently larger with more local resources (e.g., NYC cases and some of the FBI and UNT cases) to put towards investigations in general, which may indicate that these agencies have a better chance of identifying individuals. Additionally, those agencies using external forensic anthropologists (such as the agencies represented in the FBI and the UNT samples) could also represent smaller but actively engaged agencies with a better understanding of how to leverage the available resources at the local and national level (e.g., UNT and some of the FBI cases), which may in turn increase their odds of identification. Finally, the discrepancy in identification rates between NamUs and the present study could be directly related to the role of the forensic anthropologist, in that the estimation of a biological profile may increase the chance of identification and/or the kind of general engagement forensic anthropologists have with casework improves the odds of an identification. Because there are potentially confounding factors in an investigation that could result in a spurious association of the availability of forensic anthropology estimates and the chance of identifications (e.g., poorly preserved/recovered skeletal remains), we cannot infer a causal relationship from these results. While the effects size for the NYC univariate tests were small, the significant results of the multivariate analysis (which took agency differences into account) and the consistency with broader national trends suggest improvements to identifications when the biological profile is provided and that more research would be useful to infer whether this positive impact (though small effect) of forensic anthropology reporting holds beyond the present study sample.

Lastly, we addressed the specific question of identification discrepancies when ancestry estimates are provided to investigators by examining whether identification trends vary with the availability of reported biological profile estimates. After the multivariate finding that the availability of biological profile information has a significant relationship with the odds of an identification, it is important to understand whether biological profile information has the same relationship with identifications for different decedent demographic groups. Namely, we examined the postulation that biological profile estimations of ancestry can inadvertently prioritize identifications of one decedent over another, specifically cases of White decedents [ 1 , 34 ]. In this context, any case where ancestry was estimated has the potential to bias investigators in the direction of prioritizing White individuals and deprioritizing all others, which would result in a larger proportion of White individuals in the identified case subsample with ancestry estimations, and a smaller proportion of White individuals in the identified case subsample without ancestry estimations. Any identified individual without an ancestry estimation would have had no information that could bias the investigation toward prioritizing decedents of a certain race over others. Using the identified case sample, we found no differences in decedent race and/or ethnicity proportions when ancestry was and was not estimated ( Fig 5 ), suggesting limited evidence that prioritization of certain groups over others is occurring for the present study sample for this analysis.

Interestingly, in the agency-specific analyses, UNT exhibited a significant trend that is opposite of the exhibited identification rate trends of White decedents twice as frequently identified as Hispanic decedents. When ancestry was estimated, the proportion of Black and Hispanic individuals increased , while the proportion of White decedents decreased when compared to unidentified remains cases where ancestry was not estimated. This trend suggests a clear relationship between decedent race and/or ethnicity, identification, and available ancestry estimations. While prioritization of Black and Hispanic individuals in investigations is one way to interpret these findings, an alternative explanation is that estimations of ancestry improve the odds of an identification for Black and Hispanics decedents more so than for White decedents. This aligns with previous work [ 64 ] that indicates the evidentiary value of an ancestry estimation towards an identification is largely based on the racial diversity of the pool of missing persons. Given that UNT cases originate from all over the United States, the nationwide pool of missing persons is largely represented by White individuals (59%), making an ancestry estimation related to White the least unique/lowest evidentiary value for contributing to an identification. Alternatively, ancestry estimations related to Black and Hispanic decedents would have greater evidentiary value, as Black and Hispanic individuals comprise only 16% and 11% of the missing person pool, respectively (NamUs [ 65 ]). However, if evidentiary value was the main factor contributing to the observed differences, then we should have found a similar trend in the FBI as we did with UNT, given that the FBI sample also consists of nation-wide cases. Other factors, such as the lack of missing persons report being filed would also impede the ability for biological profile estimations to assist in an identification. Further study of these trends and potential factors contributing to them will help to elucidate the relationship among decedent race and/or ethnicity, the availability of ancestry estimations, and identifications in casework.

Providing context: Factors influencing investigative trends

In this study, the majority of investigative trends related to decedent demographics are negligible to small effects. Notably, decedent ancestry, race, and/or ethnicity exhibited medium effects for Aims 1 and 2 in the univariate analysis for the UNT sample. These findings provide evidence consistent with our hypotheses for Aims 1 and 2, in that decedent demographics are related to identification rates. One interpretation of these findings is to conclude that (de)prioritization of cases based on the decedent demographic is what is driving these results. However, the results were inconsistent across univariate and multivariate tests, as well as at times contradicting when comparing various measures of (de)prioritization we employed. For example, while identification rates appear to be significantly related to decedent demographics, identification duration did not always demonstrate similar results. Furthermore, Aim 3 found no differences in decedent race and/or ethnicity proportions subsamples when ancestry was and was not estimated ( Fig 5 ), suggesting limited evidence for prioritization. Collectively the inconsistency in the results are unsurprising, given that whether or not active (de)prioritization is occurring by investigators, that is just one of myriad factors which contribute to each cases’ probability of being identified. In the following paragraph, we discuss some of these factors and how they offer additional considerations beyond only (de)prioritization to contribute to the observed trends in our study.

When considering decedent sex, females exhibited significantly greater identification rates compared to males, although the overall difference is less than 10% with a negligible effect per Cramer’s V . There are several contextual factors that could play a role in the increased identifications of females, such as females being reported missing more often than males, and/or overall fewer missing and unidentified females such that there is inherently a smaller pool of potential matches in the investigation of unidentified females. National statistics on missing and unidentified persons reflect these trends of greater reporting yet lower prevalence among the unidentified, with females only comprising 19% of the unidentified persons in NamUs, yet 39% of the reported missing persons (NamUs [ 65 ]).

Age groups were found to be significantly related to identification rates for the pooled sample, with Juveniles, Adolescents and Older Adults having better identification rates than Middle and Young Adults. However, this same trend was not found to be significant in the multiple logistic regression, nor the agency-specific univariate tests, with the exception of the FBI sample which showed only a small effect driven by the Adolescent group outperforming (greater identification rates) Young, Middle, and Older adult groups. It is possible that law enforcement may not always take missing persons reports for missing young and middle-aged adults because they could be viewed as going missing voluntarily, thus contributing to these cases remaining unidentified. In addition, juvenile, adolescent and older adult age subsamples are intentionally included in various societal systems of surveillance that work simultaneously to aid in identifications and may in part explain the improved identification rates compared to other age subsamples. According to a 2021 National Center for Missing and Exploited Children (NCMEC) report [ 66 ] in which identifications of deceased children were analyzed, individuals aged 11–20 represent the largest percentage of deceased and identified children (65%)in the study. Thus, among child/adolescent deaths, this age range is both the most commonly deceased and the most commonly identified. Children in this age range have various forms of surveillance as part of their daily lives (e.g., school, parents, caregivers), and as such their disappearance is commonly noted within this system. According to the NCMEC report, the majority of deceased children were recovered in the same city or state where they went missing, and identifications primarily stemmed from law enforcement tips. This “closed system” empowers these local systems of surveillance and potentially increases identifications. In addition, cases of child/adolescent death/disappearance are subject to multiple local agencies’ investigations (law enforcement, child protective services) and may receive assistance from national entities (NCMEC, Amber alerts etc.) all working simultaneously to increase identifications.

Older adults may also have a similar system of societal surveillance related to where they die and who is looking for them. According to Muramatsu and colleague’s [ 67 ] study on place of death for older Americans, 33% died in nursing homes, <25% died at home, and the remainder died in either hospice or hospital care. Thus, the largest majority of older adults have a direct relationship to surveillance via care. Older adults often have consistent care appointments, or relationships with targeted programs like meals on wheels that surveille well-being in some metric. In addition, for older adults that may go missing, the American Silver Alert system is a public notification system countrywide that issues alerts on missing seniors, especially those that may have dementia or other cognitive impairments. Together these systems of surveillance amount to an established network of social programs that may work collaboratively to increase the identification of both adolescents and older adults in the United States.

In regard to decedent race and/or ethnicity, Aim 1 found that the pooled sample yielded no significant relationship between identification rates and decedent race and/or ethnicity s, but UNT’s agency-specific test was significant ( Table 5 ), and correspondence analysis indicated that the difference was driven by the higher identification rates for White decedents (81%) compared with Hispanic decedents (42%). UNT has more young adult, Hispanic male cases than both NYC and FBI, which is a common demographic of decedents believed to have died during an attempt to cross the U.S.-Mexico border, and multiple studies have documented the difficulties in successfully identifying decedents within this context [ 68 – 74 ].

Martinez and colleague’s work [ 70 ] examining Pima County Office of the Medical Examiner (PCOME) case data, highlighted a relationship between decedent demographics and identification rates, namely that as the number of non-Mexican, Central American individuals crossing the border increased in recent years, so too did the number of unidentified remains cases. The authors posited that poverty, consulate resource limitations, and the strategies of human smugglers along the border all increase the complexity of the investigation and create disparities in the odds of a successful identification of decedents from Central America as compared to more traditional migration regions like Mexico. Hughes et al. [ 69 ] and Algee-Hewitt et al. [ 68 ] found a similar identification disparity in PCOME forensic casework related to the ancestry of deceased individuals along the U.S.-Mexico border, in that identified migrants tended to have more European ancestry, while unidentified migrants tended to have less European ancestry. Importantly, the identification bias was unlikely to be attributed to any direct action (or inaction) by the investigators, as these particular ancestry estimates were unknown to the investigators (and the forensic anthropologists working the cases) at the time of the investigations; the ancestry estimations were instead derived from CODIS markers and/or craniometric analyses by the authors well after most of the cases had undergone their initial investigations.

These studies represent a context where all the cases were considered to be a part of a vulnerable demographic—undocumented individuals migrating across the U.S. Mexico border—yet there were still biases in the odds of being identified. Similar to Martínez et al. [ 70 ], these studies proposed that structural vulnerabilities for individuals migrating from Mexico have emerged from the economic, political, and social processes in Mexico and the United States such that certain populations (in this case, more rural, southern Mexico, and/or Indigenous) were less often able to access and/or trust government and non-governmental social services that aid in the identification of missing loved ones, such as the collection of DNA family reference samples or filing of missing persons reports, which are key to making identifications. Indeed, this finding is echoed by research focusing on how sociohistoric factors and structural vulnerabilities play a role in investigation outcomes for undocumented Latinx individuals [ 68 , 71 ]. These previous studies, along with the present study’s findings that only the UNT sample exhibited race and/or ethnicity disparities in identification rates, strongly suggest that context-specific dynamics can potentially influence the odds of an identification. As a result, the large number of U.S-Mexico border cases may inherently negatively impact the identification rates for UNT’s Hispanic subsample. However, data on the exact ratio of UNT Hispanic cases from NamUs Region 4 (which includes Texas) that are related to the border crisis was not available for the present study, and therefore we cannot conclude that these trends related to identification rates are solely a result of the United States-Mexico border context. More research on these trends may elucidate the most significant sources of the differing identification rates.

Does agency context matter?

Agency differences in identification trends highlight that the practice (and its outcomes) of forensic anthropology will inherently vary according to the context and mandates of each agency. This has important implications for research and casework, in that there may not be nation-wide trends, or, while inferable, may not be useful for understanding the ground-level practice of forensic anthropology in the United States. In this study, we have worked to incorporate models that can investigate identification trends while simultaneously accounting for agency-specific nuances. Here, we review some of the factors that may contribute to the differences we observed in identification trends across the agencies.

We found that NYC exhibited outcomes that suggest a consistent level of high performance that merited deeper examination. NYC had the greatest identification rate and exhibited a positive significant effect of reporting the biological profile on identification rate. There are substantial differences in the three agencies’ sample contexts and investigative approaches that may contribute to these trends. Both UNT and FBI forensic anthropology services span almost the entire country and they provide consultations to medical examiner/coroner and law enforcement agencies nationwide, and it is possible that the FBI and UNT may be getting a subset of cases that are inherently more difficult to identify (i.e., incomplete skeletonized remains). The FBI and UNT datasets primarily include forensic anthropology cases which are under external jurisdiction, and therefore UNT and FBI’s involvement in their cases is limited to the services requested by the originating agency. In contrast, the NYC sample in general represents cases from New York City, and within the jurisdiction of the NYC OCME. Thus, NYC OCME is in complete control of the entire investigative process, with the forensic anthropology unit deeply embedded in the investigations. These are key differences in that the results here are not truly a reflection of UNT and FBI as investigative agencies. Instead, the trends reported here for UNT and FBI reflect nation-wide trends of investigative agencies that use FBI and UNT services. Because data on the investigative agencies with jurisdiction for the cases included in the FBI and UNT samples are not available, we are unable to discuss the agency-specific practices and contexts. In contrast, because the NYC sample is by and large specific to NYC OCME jurisdiction, we focus here on the practices and investigation processes at NYC OCME in relation to their observed identification trends. We review additional factors that may contribute to identification trends across agencies in the Supporting Information.

Conclusions

The discipline of forensic anthropology has recently begun to more deeply reflect on the impact of our practices. Here, we contribute to this essential work by examining how forensic anthropology estimations of biological profile components and decedent demographics are related to identification trends. The results presented in this study indicate that for forensic anthropology cases: i) there is limited consistent evidence that decedent sex, age, and race and/or ethnicity are related to identification trends in the pooled United States sample; ii) when substantial differences (e.g. medium effects) do occur, they appear to be more agency-specific and related to the particular contexts of that agency; iii) there is no consistent evidence for discrepancies in the duration of an investigation based on a decedent’s sex or age, while race and/or ethnicity need more investigation; iv) forensic anthropological estimations of sex, age, and ancestry appear to have a small positive relationship with improved identification rates for casework.

Importantly for the present sample, forensic anthropology cases do not appear to exhibit consistent identification disparities other than those already known (such as the difficulty of identifying undocumented migrants). These results in no way negate the extensive documentation of racial bias in the criminal justice system, the possibility of delayed/deprioritization of particular investigations by law enforcement, nor the structural vulnerabilities specifically related to marginalized groups be it related to gender, race, ethnicity, socioeconomic status, or other factors. Furthermore, while our study includes cases from all NamUs regions in the U.S., our results may not necessarily determine whether disparities exist or impact identification investigations in the general U.S. practice of forensic anthropology, given that agency context and practice likely play the biggest roles in identification trends. In fact, the three study samples selected for this study reflect the best-case-scenario, in that these three agencies are state-of-the art in terms of resources, technology and quality assurance, and have multiple full-time forensic anthropologists on staff. While the best-case-scenario to practice forensic anthropology, these study samples may not be representative of all coroner and medical examiners offices in the U.S. Therefore, the current findings are a first step, and indeed, indicate that when intentional measures are taken to utilize the best investigative practices currently available, decedent demographics of deceased individuals have limited effects on reducing the chances of being identified and reconnected with their loved ones. Conversely, the findings specific to UNT’s identification rate disparities between Hispanic and White decedents suggest that some investigative contexts, such as the crisis at the U.S.-Mexico border, have hurdles that may not be fully overcome even in an agency with robust investigative means.

The findings presented here provide ample opportunity on which to expand further. Studies have hypothesized how other contextual factors that contribute to structural vulnerability and marginalization, such as gender identity, sexual preferences, race, citizenship, stigma, and socioeconomic status may contribute to identification disparities beyond the biological profile [ 5 , 20 , 69 , 75 – 78 ]. While this study found that decedent sex, age, and race/ethnicity have a limited relationship with identification trends for the study samples, other factors like socioeconomic status (SES), which are an important contributor to marginalization in the United States [ 79 ], was not taken into account. Unfortunately, there does not appear to be systematic data of the demographics and SES of individuals within the United States medicolegal death investigation system. However, based on research examining mortality in the United States more generally, SES appears to be the leading factor contributing to mortality overall, with sex and race being important factors affecting mortality within SES groups [e.g., 80 – 82 ].

Within the context of the conversation around whether and/or how to practice ancestry estimation, the results of this study offer a single data point on whether the race of a decedent is related to the odds of being identified and cannot speak to whether estimating ancestry is harming BIPOC communities within other contexts of the identification process or the lived experiences of these communities at large. Thus, the conversation is ongoing and the future discussions on ancestry estimation must still include much of what was originally called for by Bethard and DiGangi [ 1 ] as well as Stull and colleagues [ 2 ].

Using over 1,200 unidentified and identified forensic anthropology cases from three United States agencies, this study provides the first comprehensive, data-driven insight into the specific relationships between decedent data, biological profile estimations, and identification status for United States forensic anthropology cases. Even with this data, our analyses and findings are limited to the demographics that had adequate sample sizes or appropriate approaches for making inferences about the data. As such, key groups (e.g., multiracial, transgender individuals) were unable to be analyzed, and future studies will greatly benefit from a more inclusive dataset. We also acknowledge that the kind of data used in this study, namely retrospective case metrics from U.S. investigative agencies, are only one contribution to these important discussions in our discipline and is not without its own limitations. Social science approaches like ethnography will greatly contribute in ways that the data presented here cannot, and would certainly be better at measuring (de)prioritization than the proxy variables implemented here. As additional research incorporating comprehensive data continues to be developed, our understanding of biases related to the biological profile and other relevant factors will be improved, and our strategies for addressing those of significance can be refined.

Supporting information

https://doi.org/10.1371/journal.pone.0290302.s001

Acknowledgments

The authors wish to thank all three institutions (FBI, NYC OCME, UNTCHI) for allowing access to these data. The authors acknowledge the contributions of the forensic anthropologists and other medicolegal personnel employed by these institutions for their efforts in medicolegal death investigation and decedent identification. Finally, the authors acknowledge that these data represent the forensic anthropological estimates and reported demographics of deceased individuals. The use of such anonymized data allows the discipline of forensic anthropology to improve and reflect upon its’s practices.

This is publication number 22.12 of the FBI Laboratory Division. Names of commercial manufacturers are provided for identification purposes only, and inclusion does not imply endorsement of the manufacturer, or its products or services by the FBI. The views expressed are those of the author(s) and do not necessarily reflect the official policy or position of the FBI or the U.S. Government. Authors Servello, Soler, and Thomas are employed at entities from which data for this research was collected. The data that support the findings of this study are available from FBI, UNT, and NYC OCME. Restrictions may apply to the availability of these data, please contact the respective agency to inquire.

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Acad Forensic Pathol
v.6(3); 2016 Sep

Evolution of Forensic Anthropological Methods of Identification

Jason m. wiersema.

Harris County Institute of Forensic Sciences - Forensic Anthropology Division

Forensic identification of human remains has long been a core contribution of forensic anthropologists to death investigations. The array and scientific robusticity of the identification methods employed by the anthropologist has evolved in the last several decades, and as with other nonidentification methods, anthropologists have embraced the progression toward the use of validated and statistically defensible methods for identification. This article presents an overview of the role that the forensic anthropologist plays in the identification of human remains and the evolution of anthropological methods of identification.

Introduction

Forensic identification of the deceased is of primary importance in the medicolegal investigation of death. This is true in the daily investigation of individual unexpected deaths and in investigations of mass fatality incidents involving large numbers of human remains and/or fragments of human remains. Since Krogman's 1939 article in the Federal Bureau of Investigation Newsletter entitled “ A Guide to the Identification of Human Skeletal Material,” the anthropologist has maintained a significant and expanding role in identification ( 1 ). Much has changed since the days of anecdotal comparison of skeletal features for identification with advancements in the development of standard and validated methods for identification in the wake of the Daubert v. Merrell Dow ruling ( 2 ) and the more recent National Academy of Sciences (NAS) report ( 3 ). The NAS report called on the forensic sciences to validate existing methods and to develop new methods that can be validated via assurance of repeatability, reliability, and accuracy. Recognition by forensic anthropologists of the need for standardized, validated methods for identification predates the NAS report ( 4 – 6 ), as does much of the research aimed at validation of anthropological methods of identification. Anthropologists have continued to contribute to this discussion since the NAS report was published ( 7 – 11 ).

Anthropological Methods for Identification

The contribution of the forensic anthropologist to the identification process varies by jurisdiction, in large part due to whether or not the anthropologist is a full-time employee of the medicolegal jurisdiction rather than a contractor. Those who are embedded in a medical examiner/coroner operation are typically involved in a greater variety of components of the identification process than those who consult, including both the application of anthropological methods and administrative contributions ( 12 ). This article focuses on the core contribution of the forensic anthropologist to identification: the direct comparison of antemortem radiographs attributable to suspected deceased persons to postmortem radiographic images collected from the deceasent by the medicolegal agency. The anthropologist also impacts the identification process via the extraction of biological indicators of age, sex, ancestry, and stature from unidentified human remains that allow for the development of a biological profile that limits the number of people to whom a decedent bears resemblance ( 13 ). Facial approximation and superimposition are methods employed by some anthropologists that are generally useful as tools for eliminating identification candidates or for narrowing candidate pools rather than for identification. These methods are thus not discussed in any detail in this article.

Forensic anthropologists leverage their detailed familiarity with the skeleton and its variability to assess the likelihood that the similarity between two images of the same skeletal feature constitutes identification. This comparison involves consideration of overall bone morphology and contour, trabecular bone patterns, sinus morphology, and the presence and morphology of orthopedic or surgical devices. In general, the greater the morphological complexity, the higher the likelihood that a particular bony feature will have discriminatory value. Thus, most of the bones of the body have the potential to contribute to identification, but certain elements of the skeleton (e.g., frontal sinuses, petrous temporal bone, dentition) are preferable because of their morphological complexity. Some elements that have complex morphology have compromised utility because of their location in the body and their appearance on antemortem imaging. The vertebral column, for example, has very complex morphology, particularly in aged individuals with degenerative changes, but is often viewed by the anthropologist in anterior-posterior chest radiographs and is thus viewed through the anterior ribs, sternum, and thoraco-abdominal organs. Another consideration is the prevalence of imaging in the antemortem record. For example, chest radiographs, though difficult to use for identification for the above stated reason, are commonly used for identification because of their high level of availability. In the author's experience, there also seem to be distinctions between the lay population and the deceased medicolegal population (e.g., higher incidence of interaction with the healthcare system and/or criminal justice system) in terms of antemortem record prevalence, which can benefit the anthropologist seeking antemortem records.

The first account of comparison of radiographs for the purpose of forensic identification of the deceased was described in the third decade of the last century ( 14 ). The authors used the morphology of the nasal accessory sinuses and the mastoid processes to confirm the identity of a heavily decomposed person. The subsequent literature, particularly between 1995 and 2008, is replete with published attempts to find means of extracting diagnostic information directly from skeletal remains via comparison of ante- and postmortem radiographs. Numerous publications describe individual identifications made using radiographic imaging of various parts of the postcranial skeleton including the leg and foot ( 15 ), chest ( 11 , 16 ), clavicles ( 17 , 18 ), pelvis ( 19 , 20 ), vertebral column ( 9 , 21 ), and the hand and wrist ( 6 , 22 ), as well as features of the cranium, including the mastoid sinuses ( 23 ), nasal sinuses ( 14 ), cranial suture patterns ( 24 ), frontal sinuses ( 25 – 34 ), and orthopedic/surgical devices from various parts of the body ( 35 , 36 ).

The frontal sinuses have received considerable attention as a highly variable and individualistic character of the human skull ( 25 – 31 ), and provide a synopsis of the progression of the identification literature from anecdotal accounts of comparisons to the development of methods for comparison of images complete with statistical measures of likelihood. An exhaustive review of the literature pertaining to identification methods based on every part of the skeleton is beyond the scope of this article. The following paragraph uses the frontal sinus as an example of the development of, problems with, and considerations associated with radiograph identification methods.

Articles discussing the radiographic evaluation of the frontal sinuses in personal identification have been published on several occasions ( 25 , 27 , 28 , 37 , 38 ). However, the majority of the early publications are case reports and do not present techniques for future application, nor do they satisfy the requirements of the Daubert guidelines or address the limitations identified in the NAS report. For example, Quatrehomme and Fronty suggests simple superimposition of ante- and postmortem conventional radiograph images as a viable technique for personal identification from the frontal sinus ( 39 ). The authors acknowledge the considerable difficulty associated with the correct orientation of the skull for postmortem imaging, but do not address the subjectivity associated with the method. Quatrehomme and Fronty's method is typical of these articles, which present a case, or series of cases, in which “identifications” were made based on matches perceived by the observer ( 25 , 28 , 38 ). Kirk et al. published the results of a survey of 39 cases in which identifications were made in Ontario, Canada, based on nonmetric comparison of frontal sinus configuration ( 40 ). Only three of the 39 cases were considered unidentifiable using the frontal sinus because of poor film quality and the remaining 36 produced “conclusive postmortem to antemortem pattern matches” ( 40 ). The identifications were made based on uniqueness, as perceived by the viewer, between superimposed ante- and postmortem anteroposterior radiographs of the skull. They also refer to the “quantitative” association of 16 cases. This quantification involved measurement of the maximum vertical and horizontal dimensions of the sinuses. “Any discrepancy between antemortem and postmortem values greater than 5 mm was classified as a metric nonmatch” ( 40 ). Although less subjective than the identifications made solely on the basis of simple superimposition of ante- and postmortem imaging, this technique does not provide either a statistical measure of the strength of the associations or error rates associated with its use. More comprehensive systems for classifying and/or identifying crania according to variability of the frontal sinuses have been presented by Yoshino et al. ( 29 ), Yoshino et al. ( 41 ), Schuller ( 26 ), Reichs ( 31 ), and Reichs and Dorion ( 30 ). Yoshino et al. developed a potentially repeatable methodology for personal identification from conventional radiographs of the frontal sinuses ( 29 ). The method involved the development of a code number from the classification of six independent characteristics of the frontal sinuses. The code was a series of numbers that was statistically unlikely to be derived from more than a single individual by virtue of its length and the number of possible combinations represented by all of its possible variations. Yoshino used the skulls of 35 Japanese adults (21 males and 14 females) to develop the technique. They tested the technique on a single forensic case and concluded that the technique is of “considerable value in cases in which dental remains are not available” ( 29 ). Reichs and Dorion ( 30 ) and Reichs ( 31 ) modified this technique for use with axial computed tomography (CT) scans of the skull. Their argument is essentially that future use of CT imaging will far outweigh the use of fronto-occipital radiographs, and that identification techniques based on radiographs will someday become obsolete. Thus instead of conventional radiography, they developed a method similar to that of Yoshino et al. using axial CT imaging ( 29 ). They evaluated a slightly different series of characteristics than Yoshino et al. that were more effectively imaged on CT scans, including bilateral dimension, bilateral asymmetry, superiority of side, distribution of partial bony septations, number of partial bony septations, distribution of complete bony cells, and number of complete bony cells ( 29 ). They suggested that scoring these attributes on several consecutive CT slices added to the length of the code derived, and therefore, to its statistical uniqueness.

Development of Quantitative Methods for Identification

There has been a surge in publications regarding the validation of all aspects of forensic anthropological analysis in the last ten years, particularly since the publication of the NAS report. For many of the analyses conducted by forensic anthropologists, including sex and age estimation, this involves the statistical validation of existing anthropological methods like pubic symphysis or sternal rib end aging. On the other hand, identification of decedents via radiograph comparison has been historically subjective. The discriminatory value of subjective comparison of skeletal radiographs is valuable and these methods are likely to persist as an identification tool for use by the forensic anthropologist. This is true in part because the anthropologist cannot validate radiograph identification methods for every bone in the body, nor can we anticipate what bone(s) may be available for comparison in a given case. However, the importance of the development of validated identification methods is well recognized. “Because forensic anthropologists are trained first and foremost as physical anthropologists, they emphasize estimation problems at the expense of evidentiary problems” ( 42 ). Steadman and colleagues outline the application of Bayesian statistics, in particular likelihood ratios, in the validation of anthropological methods of identification. They explain the conceptual and practical differences between appropriate reference samples and the population at large. The authors identify several databases that can be used as references for population at large estimates, as well as novel data that can be used to calculate the frequency of specific identifiers within the population at large.

The primary problem with historical usage of radiograph comparison is the real or perceived lack of repeatability of the comparisons. Repeatability is dependent on the objectivity of the methodology employed, and objectivity is difficult to establish when using methods dependent on the investigator's individual assessment of subjective characteristics, such as a particular shape, level of symmetry, or side dominance. For example, the features of the frontal sinuses evaluated in the publications by both Yoshino et al. ( 29 ) and Reichs and Dorion ( 30 ) are arbitrary. There is a need for more easily reproducible character evaluations. Some authors have tried to increase the objectivity of radiographic methods by various means. As mentioned above, Kirk et al. attempted to add quantitative robusticity to the radiographic analysis of frontal sinuses by recording the maximum width and length of the sinuses in a sample of 39 crania, in addition to the more subjective variables used in other investigations ( 40 ). Reipert et al. completed an investigation that aimed to “improve the objectivity of X-ray comparison for the identification of unknown individuals” by using a computer program named FoXSIS to reduce subjectivity in the analysis of the frontal sinuses ( 43 ). Computed tomography data were collected for 30 skulls, and were converted to virtual X-ray representations of the skulls. According to the authors, the primary advantage of the program was that its use of digital measurements of the features of the skull allowed for a quantification of the “probability of identity” without reliance on the more subjective, and less repeatable measures of identity such as side dominance, shape, and symmetry levels.

There is also a problem with techniques that are based on the assumption that it is statistically improbable for two individuals to have the same or similar codes just because there are a large number of possible combinations. This is problematic (at least with the techniques outlined above) because no effort is made to weigh the various characters relative to one another. For example, it is much more likely for an individual to have a single or very few septations of the frontal sinus than for them to have six or seven, thereby increasing dramatically the statistical probability that two individuals may indeed have the same code for that particular trait. This is a problem with many of the characteristics considered by both Reichs ( 31 ) and Yoshino et al. ( 29 ). Christensen published the most objective and statistically robust analysis of the frontal sinuses to date ( 32 ). She used elliptical Fourier analysis (EFA), a geometric morphometric technique that imposes a set of coordinate data points to a closed curve, to quantify the superior border of the frontal sinuses. The coordinate data were then used to quantify the outlines by generating a set of coefficients that represent a numerical reproduction of the curve. She traced the superior border of the frontal sinuses of 808 individuals and closed the curve inferiorly by connecting the inferior-most extensions of the left and right sides of the curve with a straight horizontal line. The Euclidean distances between the EFA-generated outlines were compared as a means to test the accuracy with which they could be used to associate the correct images. The Euclidean distances between repeat images from the same individual were significantly smaller than the distances between individuals. She used typicality statistics to evaluate the statistical strength of the associations with good results. The probability of making an incorrect association between two outlines using her method is very small, and she concludes that “there is a quantifiable and significant difference between the shapes of individual frontal sinus outlines” ( 32 ).

Wiersema developed a method for comparison of ante- and postmortem axial CT images of the petrous portion of the temporal bone ( 44 ). The data used in the study were collected from repeat axial head CT images of 115 individuals, and the Euclidean distance comparisons were made between images of the same individual and images from different individuals. Two-dimensional coordinate data from 36 landmarks on each of the CT images were calculated and the distances between each of the coordinate points were captured to generate the data used in the statistical analyses. Measurement subsets were developed based on two separate models, the first of which used anatomical criteria identified by the study author and the second used principal components factor analysis to identify the subset with the most statistical significance (Images 1-3) .

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The first two columns illustrate the landmark locations in the inner and middle ear segments of the petrous part of the temporal bone used in this research. The third column illustrates the measurements between the landmarks in the inner and middle ear segments. The measurements are color-coded according to the legend located between columns 2 and 3.

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The first two images (labeled slices E&F) illustrate the locations of the landmarks around the contour of the petrous part of the temporal bone. The third image illustrates the measurements between the landmarks around the contour of the petrous part of the temporal bone. The measurements are color-coded according to the legend located between the second and third images.

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Object name is 10.23907_2016.038-fig3.jpg

The first two columns illustrate the remaining landmark locations in both the inner and middle ear, and the contour segments of the petrous part of the temporal bone. The third column illustrates the measurements between the measurements that extend between the landmarks of the inner and middle ear, and the contour of the petrous part of the temporal bone. The measurements are color coded according to the legend located between columns 2 and 3.

The measurement sets of both models were then compared to one another using nearest neighbor analysis, to test their relative efficiency in matching replicate images to one another. The results of both models were highly accurate. Three incorrect nearest neighbor matches resulted from the biological model and five from the principal components factor analysis model. The errors appear to have been the result of variation in the axial plane between the first and second scans. The results of the nearest neighbor comparisons were then considered within the context of Bayes' Theorem by calculating likelihood ratios and posterior probabilities. The likelihood ratios and posterior probabilities were very high for both models, indicating that 1) there is significant individual variability in the measurements of the petrous portion used in this research and 2) this variation represents a high level of potential accuracy in the application of this method in the identification of forensic remains.

Derrick et al. describe an automated method for comparison of lateral images of the cervical spine that was mathematically validated for use by medical examiner's/coroner's offices ( 9 ). The software quantifies the likelihood that any two of the radiographs in an array of cervical spine images ( Image 4 ) contain matching vertebral body morphology. Six validations were conducted to evaluate the repeatability, reliability, and sensitivity of the method. The authors report a 92-100% success rate in matching the test image to the correct image in the array. The success rate for cervical vertebrae is particularly high, less so for lumbar vertebral bodies (which tend to be less morphologically distinctive and often partially obstructed by intermediate objects).

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Sample test array.

The limitation of this particular method is the limited availability of antemortem lateral cervical spine radiographs. The utility of the method would be greatly enhanced if antemortem lateral CT scout images of the head and neck were deemed appropriate for comparison.

Forensic Anthropological Identification in the Mass Fatality Context

The role of the anthropologist in the mass fatality context is discussed at length elsewhere ( 45 ). However, that article does not address the methodological issues associated with the identification of fragmentary remains, or of common, unidentifiable tissue that is sometimes present following a mass fatality incident. Many of the radiographic techniques employed for daily cases are not useful for postdisaster fragmentary remains. Some of the more diagnostic portions of the skeleton, including the frontal sinus, are at considerable risk of destruction. Focus of current/future methods for use in the mass fatality context should involve segments of the skeleton that resist taphonomic destruction, including the petrous portion of the temporal bone. It may also be difficult to employ radiographic techniques due to availability of antemortem radiographs, as the victims of mass fatality incidents are often more similar to the lay population rather than the deceased medicolegal population.

The forensic sciences have undergone a considerable transformation in recent decades toward a more robust network of services that are based on validated methods and accredited laboratories. Anthropological methods have evolved concomitantly from the anecdotal to the statistically validated, accurate, and repeatable methods that are being developed today. The need for more subjective anthropological evaluation of radiographs will continue to have a place in forensic anthropology for identification, but validation of these methods is as important as it is for other anthropological methods (sex, age and ancestry estimation).

Disclosures

The author has indicated that he does not have financial relationships to disclose that are relevant to this manuscript

ETHICAL APPROVAL

As per Journal Policies, ethical approval was not required for this manuscript

STATEMENT OF HUMAN AND ANIMAL RIGHTS

This article does not contain any studies conducted with animals or on living human subjects

STATEMENT OF INFORMED CONSENT

No identifiable personal data were presented in this manuscsript

DISCLOSURES & DECLARATION OF CONFLICTS OF INTEREST

The authors, reviewers, editors, and publication staff do not report any relevant conflicts of interest

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forensic anthropology
forensic anthropology, application of physical anthropology to legal cases, usually with a focus on the human skeleton. Forensic anthropology uses the techniques of physical anthropology to analyze skeletal, badly decomposed, or otherwise unidentified human remains to solve crimes. Forensic anthropologists can assess the age, sex, and unique features of a decedent and are invaluable in ...
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Forensic Anthropology
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