Disaster victim identification: Stable isotope analysis and the identification of unknown decedents.

Within the complex world of disaster victim identification, or DVI, forensic science practitioners use a variety of investigative techniques to work toward a common goal: identification of the decedents, bringing closure to the affected communities. Identification is a complex undertaking; the event (disaster) also can be extraordinarily complex, as it may be an acute event, or one that spans months or years. Compounding this time issue, remains may be heavily fragmented, dispersed, commingled, or otherwise disrupted by either the perpetrators or the disaster itself. To help solve these complexities, we explore the use of stable isotope analysis (SIA) in DVI events. SIA can be used with a variety of body tissues (hair, nail, bone, and teeth), and each represents different time depths in a decedent's life. Bone collagen and tooth enamel carbonate are useful to reconstruct an individual's diet and source water intakes, respectively, leading to likely population or geographic origin determinations. Additionally, the carbon and nitrogen isotopic signatures of bone collagen have calculated intraperson ranges. These facts allow investigators to determine likely origin of remains using isotopic data and can be used to link skeletal elements (to an individual), or perhaps more importantly, show that remains are not linked. Application of SIA can thus speed remains identification by eliminating individuals from short lists for identification, linking or decoupling remains, and reducing the need for some DNA testing. These strategies and hypothesis tests should commence early in the DVI process to achieve maximum effectiveness.

Forensic application of isotope ratio mass spectrometry (IRMS) for human identification.

Application of isotope ratio mass spectrometry (IRMS) to skeletal remains has become an important tool to investigate human behavior and history. Isotopic variations in collagen, enamel, and keratin reflect variations in an individual's diet and drinking water. Since food and water sources typically are geographically linked, isotope testing can assist in forensic identification by classifying remains to a likely geographic or population origin. If remains are commingled, differences in diet or geographic origin also can support their separation. The usefulness of IRMS in forensic science is dependent on the underlying quality and surety of the isotope test results; in other words, we need to understand their reliability in interpretations. To take ownership of isotopic data quality, we recommend asking a series of questions:Here, we use data collected during the buildout and accreditation of an isotope testing program at the Defense POW/MIA Accounting Agency (DPAA) to answer the above questions for the forensic application of IRMS for human identification. While our primary focus is on the preparation and analysis of bone collagen, the questions above should be considered whenever isotope testing is used in forensic casework. Whether the populations of interest are drugs or humans, olives or explosives, users need to evaluate their isotopic data and interpretations to ensure they are scientifically sound and legally defensible.

A large-scale evaluation of intraperson isotopic variation within human bone collagen and bioapatite.

This study investigated intraperson skeletal (herein referred to as either "intraperson" or "intraskeletal") variation in stable isotope ratios for collagen (C and N) and bioapatite (C and O) extracted from five to six long bones from 27 modern individuals. The maximum intraperson variation observed for collagen was 0.78‰ for δ13Ccoll values and 1.12‰ for δ15Ncoll values, with a mean variation (± SD) of 0.33 ± 0.18‰ and 0.45 ± 0.27‰, respectively. For bioapatite, the maximum intraperson variation was 1.63‰ for δ13Cap values and 4.80‰ for δ18Oap values, with a mean variation (± SD) of 0.81 ± 0.32‰ and 1.00 ± 1.03‰, respectively. These results generally agree with previously reported data on intraskeletal isotopic variation. Using a two- and three-standard-deviations-from-the-mean model with analytical quality control data included, it is proposed that two bones with differing collagen δ13Ccoll values greater than 0.75‰ are probably from different individuals, and those that have differing values greater than 0.95‰ are from different individuals. Likewise, differing collagen δ15Ncoll values greater than 1.05‰ are probably different, and greater than 1.35‰ are different. For bioapatite, the proposed values change to 1.55‰ and 1.90‰ for δ13Cap, respectively; for δ18Oap values no limits were set due to the unexpectedly large variation found in the study population. We highly encourage researchers to use extreme caution when interpreting δ18O values from bone apatite. We also note that these parameters were evaluated on modern samples and therefore may not reflect intraperson variation in past societies. Finally, we demonstrate application of these interpretative limits to sort commingled human remains cases.

Ancient DNA Methods Improve Forensic DNA Profiling of Korean War and World War II Unknowns.

The integration of massively parallel sequencing (MPS) technology into forensic casework has been of particular benefit to the identification of unknown military service members. However, highly degraded or chemically treated skeletal remains often fail to provide usable DNA profiles, even with sensitive mitochondrial (mt) DNA capture and MPS methods. In parallel, the ancient DNA field has developed workflows specifically for degraded DNA, resulting in the successful recovery of nuclear DNA and mtDNA from skeletal remains as well as sediment over 100,000 years old. In this study we use a set of disinterred skeletal remains from the Korean War and World War II to test if ancient DNA extraction and library preparation methods improve forensic DNA profiling. We identified an ancient DNA extraction protocol that resulted in the recovery of significantly more human mtDNA fragments than protocols previously used in casework. In addition, utilizing single-stranded rather than double-stranded library preparation resulted in increased attainment of reportable mtDNA profiles. This study emphasizes that the combination of ancient DNA extraction and library preparation methods evaluated here increases the success rate of DNA profiling, and likelihood of identifying historical remains.

Mitochondrial DNA haplogrouping to assist with the identification of unknown service members from the World War II Battle of Tarawa.

The World War II Battle of Tarawa, 1943, was a devastating conflict that resulted in losses of more than 1100 American and 4690 Japanese troops. The United States government aims to identify and repatriate the remains of all missing American service members through the Defense Prisoner of War/Missing in Action (POW/MIA) Accounting Agency (DPAA) and its partners such as the Armed Forces Medical Examiner System's Armed Forces DNA Identification Laboratory (AFMES-AFDIL). Remains associated with the Battle of Tarawa have been recovered from field excavations conducted by History Flight, a DPAA strategic partner, as well as from the National Memorial Cemetery of the Pacific (NMCP) in Hawaii where unknowns have been disinterred for identification. DNA testing at the AFMES-AFDIL has produced mitochondrial DNA (mtDNA) sequences from 1027 case samples to date. Haplogroup assignments indicate that more than one third (36.2 %) of field-collected samples are likely of Asian maternal ancestry. Therefore the field collections from the Tarawa battlefield comprise the remains of American service members but also those of foreign nationals from Asia. The mtDNA of the NMCP unknowns is similar in ancestry proportion to the family reference sample distribution. The DPAA uses the ancestry information gleaned from mtDNA sequence data in conjunction with anthropological evidence to make foreign national determinations. In this way, mtDNA haplogrouping is used to sort the commingled and fragmentary remains recovered from Tarawa between Americans and foreign nationals, which are then repatriated to their country of origin.

Introducing Human Mandible Identification [(hu)MANid]: A Free, Web-Based GUI to Classify Human Mandibles.

Statistical programs have revolutionized the way in which forensic anthropologists conduct casework by allowing practitioners to use computationally complex analytics at the click of a button. Importantly, the products of these statistical programs are reproducible and contain measures of error or uncertainty, thereby strengthening conclusions. This paper is an introduction to (hu)MANid, a free, web-based application that uses linear and mixture discriminant function analyses to classify human mandibles into one of many worldwide and/or periodic reference groups. The mechanics, development, and use of the application will be discussed. Further, the program was tested against other software to compare model performances and classifications. Total correct classifications among the test cases and programs were identical. Ten mandibles were tested using both statistical procedures. Mixture discriminant analysis improved classification by an average of 9.3% and correctly identified three more mandibles than LDA. Therefore, we believe (hu)MANid will be an asset to the anthropological community.

Examining Interobserver Reliability of Metric and Morphoscopic Characteristics of the Mandible.

Mandibular metric and morphological characteristics have long been used for sex and ancestry estimation. Currently, there are no large-scale studies examining interobserver agreement, particularly examining the role of observer experience. This study examines the interobserver agreement of six morphoscopic and eleven metric mandibular variables. Four observers with varied levels of experience scored 183 mandibles from the William M. Bass Donated Skeletal Collection. Absolute agreement and consistency were evaluated with the intraclass correlation coefficient (ICC). Additionally, technical error of measurement (TEM) and relative TEM (%TEM) were calculated for each metric variable. All analyses were conducted twice-once with all observers and again with only experienced observers. Results show mean morphoscopic agreement of 0.543 among all observers and 0.615 for experienced observers, and mean metric agreement of 0.886 among all observers and 0.911 for experienced observers. Further, no TEM exceeded 2 mm. All results were significant (p < 0.001).

Distribution of ametropia among military beneficiaries.

In addition to active duty military members and their dependents, retired military members and the members of their immediate families are eligible for eye care in military medical treatment facilities. We recorded refractive errors, age, sex, and race for 4,595 individual beneficiaries visiting optometry clinics at two U.S. Air Force medical treatment facilities during 2005 to 2006. Evaluation revealed most patients requiring optical correction were myopic, or near-sighted, and there was an increase in the degree of myopia between ages 4 and 23. That trend is reversed at age 30 and, by age 60, most patients are hyperopic, or far-sighted. Both trends were true for both sexes and all ethnicities studied. The degree of astigmatism was distributed similarly between races and age groups. Presbyopia occurred at similar ages and progressed at similar rates in all ethnicities and both sexes.

Pubic bone age estimation in adult women.

In recent years, numerous physical anthropologists have pointed out the need for regional standards for estimating age in various world populations. While investigating aging methods for East European populations, dramatic changes were noted in the pubic symphyseal morphology and structure of older adult female individuals. These changes were not captured in the typically used pubic symphysis aging methods. This paper defines and tests the need for a new phase, phase VII, that follows the Suchey-Brooks phase VI. In addition, Suchey-Brooks phases V and VI are redefined. Phase definitions, decision-making rules, and comparison graphics for the new method are presented. Balkan (n = 85) and Eastern Tennessee (n = 104) samples, totaling 189 individuals, were used in the analysis. Pearson correlation coefficients between four observers and a control seriation were strong, indicating ease of replicability between investigators. No statistically significant intra-observer error was detected. Summary statistics show that individuals in phase V were on average in the early 50s, while individuals in phase VI were in their mid 50s to mid 60s, and individuals in phase VII were in their mid 70s. Since linear regression models tend to under-age the elderly and over-age the young, transition analysis, using an unrestricted cumulative probit model, was undertaken to evaluate the phases and to produce point estimates for the ages-at-transition for the Balkan sample. The highest posterior density region point estimates with their associated upper and lower bounds can be used for predicting age for unknown forensic cases related to the Balkan sample. Further, the mean ages and standard deviations for phases V-VII for the Tennessee sample are presented for use in American forensic cases.

Inter-observer variation in methodologies involving the pubic symphysis, sternal ribs, and teeth.

For the skeletal age of a victim to be useful in victim identification, the methods on which it is based must be reliable, accurate, and the results easily duplicated. The ability of multiple investigators to duplicate results is an interesting and complex issue. The purpose of this study is to investigate how consistently multiple investigators assign skeletal traits to rib, pubic symphyseal, or tooth "phases" and measure teeth. The skeletal data from identified individuals in Kosovo are used to test inter-observer variation for a variety of skeletal and dental aging techniques. Two hundred and ninety-six (n = 296) pubic symphyses were scored in the manners of the Todd's ten-phase system and the Suchey-Brooks six-phase system. Six hundred and twenty-two (n = 622) sternal rib ends were scored in the manner of Iscan and co-author's nine-phase system. Four hundred and twelve (n = 412) single-rooted teeth were measured in the manner of Lamendin and colleagues and scored for the amount of tooth wear using Smith's nine-phase system. Repeat measures were taken by multiple observers. There appears to be a wide range of variation, even among experienced investigators in the assignment of phase or metric data. Inter-observer variation, investigated through Pearson's r correlation coefficients, the Wilcoxon signed ranks test, and paired samples t-tests demonstrate significant differences using all methods. How this variation affects the accuracy of age estimation is subject to further investigation, but what is clear is that even with collaboration among investigators to calibrate with one another, the repeatability of numerous aging methodologies is difficult to achieve. Through this investigation it appears the problem lies in the qualitative nature of broad descriptive phase categories, which contain multiple skeletal features and traits that are open to interpretation.

Forensic application of optical correction.

BACKGROUND: Prescription eyewear can be used to aid in forensic investigations. Until now, investigators and consulted eye professionals have been limited to a simple "match" or "no match" judgment. This article introduces optometry to a Web-based tool that can be used to assess the strength of a match between spectacle prescriptions and recorded patient information. METHODS: Three databases with more than 385,000 individual prescriptions were used to create the Web tool that calculates the frequency with which a prescription occurs in various U.S. populations. A search for any prescription in the tool's database will result in a report of the number of times a given prescription occurred in the queried database(s) as well as the calculated frequency with which the combination of the given sphere power, cylinder power and axis are likely to occur. RESULTS: Practical application of the Web tool in 2 published cases has shown matches with frequency of occurrence of 5.33 x 10(-6) and 2.66 x 10(-6), respectively. This application currently is being used by the Joint POW/MIA Accounting Command Central Identification Laboratory (JPAC-CIL) and other agencies when optical materials are available in forensic settings. Further, this application currently is contributing evidence in an active murder case. CONCLUSION: The creation of this easy-to-use Web tool allows eye care professionals to provide strong statistical assessments when serving as consultants to forensic investigators.

Measuring the intercondylar shelf angle using radiographs: intra- and inter-observer error tests of reliability.

This study presents a test of intra- and inter-observer measurement error rates of the intercondylar shelf angle of the distal femur, as measured on lateral radiographs. This measurement is the central element of a method to determine racial affiliation from the distal femur. Four observers independently radiographed a set of 33 complete and partial femora from collections housed at the Joint POW/MIA Accounting Command, Central Identification Laboratory. Each observer then measured the intercondylar shelf angles in each radiograph, following the original method's guidelines. A supplementary inter-observer error test was conducted by four additional observers on one set of radiographs. Statistically significant differences were found for both intra- and inter-observer error based on the results of Student's t-tests, paired samples t-tests, and ANOVA analyses. The results of this study indicate that further experimentation should be undertaken in order to develop refined measurement techniques that may help improve standardization and reduce the observer error rates.

Personal identification based on prescription eyewear.

This study presents a web-based tool that can be used to assist in identification of unknown individuals using spectacle prescriptions. Currently, when lens prescriptions are used in forensic identifications, investigators are constrained to a simple "match" or "no-match" judgment with an antemortem prescription. It is not possible to evaluate the strength of the conclusion, or rather, the potential or real error rates associated with the conclusion. Three databases totaling over 385,000 individual prescriptions are utilized in this study to allow forensic analysts to easily determine the strength of individuation of a spectacle match to antemortem records by calculating the frequency at which the observed prescription occurs in various U.S. populations. Optical refractive errors are explained, potential states and combinations of refractive errors are described, measuring lens corrections is discussed, and a detailed description of the databases is presented. The practical application of this system is demonstrated using two recent forensic identifications. This research provides a valuable personal identification tool that can be used in cases where eyeglass portions are recovered in forensic contexts.

Blunt force cranial trauma in the Cambodian killing fields.

In this paper we present a unique pattern of blunt force cranial trauma that was observed in 10 of a sample of 85 crania from a Cambodian skeletal collection comprised of Khmer Rouge victims. Initial examination of the trauma, which presents as substantial damage to the occipital with fractures extending to the cranial base, suggested the pattern was classifiable as a basilar or ring fracture. However, further investigation, including trauma analysis and historical research, revealed that this fracture type is distinctive from basilar and ring fractures. Historical data indicate that a particular execution method was the likely source of the trauma. Recognition of this trauma pattern is significant because it exemplifies the distinct fracture configuration resulting from an apparently categorical and methodical execution technique. Identification of this fracture type could potentially assist forensic investigators in the recognition of specific methods of murder or execution.