To date, numerous studies have examined the range of cranial thickness variation in modern humans. The purpose of this investigation is to present a new method that would be easier to replicate, and to examine sex and age variation in cranial thickness in a white sample. The method consists of excising four cranial segments from the frontal and parietal regions. The sample consists of 165 specimens collected at autopsy and 15 calvarial specimens. An increase in cranial thickness with age was observed. The results suggest that cranial thickness is not sexually dimorphic outside the onset of hyperostosis frontalis interna (HFI).

Forensic anthropology, forensic taphonomy and forensic entomology are specialties that greatly contribute to judicial investigations and the identification of a decomposing corpse. This research examines the effect of calcium oxide (CaO), known as “quicklime”, on the decomposition process of human remains in a tropical climate. Quicklime has been used since the Early Iron Age, in wars, mass graves and today by criminals, as there is a belief or social myth that it can speed up the process of decomposition of bodies. However, there are no studies on the effect of this chemical on decomposing bodies in a tropical climate. Puerto Rico, in addition to having this climate, has a high crime rate related to drug trafficking. This study uses a series (n=10) of pig (Sus scrofa) burials as a model for human corpses, which were documented through photographs and state of decomposition, as well as climatic conditions, soil pH, odor of decomposition, and the lost mass. The author hypothesizes that the tropical climate contributes to the rapid decomposition of bodies by altering their appearance and morphology; since it is warmer, bacteria multiply more quickly and the entomofauna is more active, in comparison with studies already carried out in temperate climates. In addition, quicklime helps soft tissue decomposition proceed faster and reduces decomposition odor. Among the results, it was observed that there was no acceleration in the decomposition process due to the application of calcium oxide, and this chemical does not have the qualities attributed to it by social myths regarding the complete destruction of human remains, which could be considered an advantage for investigators in cases where there is a buried corpse covered in quicklime. However, it was possible to show that among other effects of quicklime, it subjectively reduces the odor of decomposition, inhibits and/or reduces the activity of the entomofauna, maintains a soil with an alkaline pH and therefore caused the mummification of the body. It can be suggested that the tropical climate helps in an effective decomposition due to the high temperatures, the humidity, and the activity of the entomofauna. Therefore, in both temperate and tropical climates, quicklime does not accelerate the decomposition process, but in a tropical climate it can inhibit the activity of entomofauna and the odor of decomposition. Statistically, results show that the Total Body Score (TBS) did not vary significantly, but the percentage of Mass Loss (ML) had a statistical difference due to the adhesion of the compacted quicklime to the experimental carcasses which increased the overall mass and not because a difference in the actual tissue loss was measured. This is since the decay process almost stopped after 77 days of burial and the mass loss nearly ceased, because with more days of rain and humidity, the more chemical reaction quicklime does (turning it into hydrated lime), causing solidification and mummification in the experimental pig carcasses. The quicklime also maintained an alkaline pH in the pig carcasses compared to the acidic pH of the controls after the decomposition. Therefore, quicklime causes a very sudden dehydration, and, in this sense, it prevents the proliferation of bacteria and, therefore, putrefaction, causing a mummification process. In addition, with the results obtained in this investigation and in other future ones, it will be possible to add scientific, anthropological, and forensic data on the analysis of the effects of quicklime in the stages of decomposition of human remain and in different deposition environments, to establish the time elapsed between death and the moment in which the body has been buried (exposed or not to quicklime) and contribute to criminal cases.

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Over the last few decades, forensic anthropological research has made significant strides in developing better methods for decedent identification and increasing the accuracy of time since death/postmortem interval (PMI) estimations within medicolegal contexts. Until recently however, there has been little emphasis placed on how socioeconomic considerations might be connected, especially regarding recovery times for individuals from various demographic backgrounds. Using intersectional and biocultural frameworks and data collected from forensic anthropologists and medicolegal labs throughout the Southeastern US, this research aims to decipher the role that inequality, through instances of social vulnerability and structural violence, plays in recovery time data throughout the region. Considerations of how systematic violence can impact socioeconomic and sociopolitical factors for a demographic groups' recovery times could highlight disparities in how politics, law enforcement, and medicolegal personnel assist and conduct casework based on sociocultural and socioeconomic factors.

Sex estimation is vital to building the biological profile in forensic anthropology. Cranial nonmetric traits are often used in adult sex estimation due to their sexually dimorphic nature. However, only one nonmetric trait is assessed on the occipital despite the bone’s postmortem durability. While these sex estimation methods were developed for use on adult crania, juvenile sex estimation is less accurate due to differences in the age at which individuals reach sexual maturity. The aim of this study was to improve upon existing sex estimation methods by accounting for shape differences that exist within the occipital. This study used computed tomography (CT) scans from the New Mexico Decedent Image Database consisting of 127 males and 124 females between birth and 25 years. Surface models of the CT scans were generated and three-dimensional coordinates (5 landmarks and 45 curve semilandmarks) were used to evaluate occipital morphology. A generalized Procrustes analysis, principal component analysis (PCA), and discriminant function analysis were applied to the scans to identify shape changes in the occipital. Nonmetric traits assessed on the surface models included nuchal crest, bun, torus, and median nuchal line. Chi-squared and Fisher’s exact tests were used to identify if significant differences existed between sexes for each nonmetric trait. The PCA results show no sexual dimorphism in occipital shape. After identifying when nonmetric traits appear dimorphic via frequency data, chi-squared and Fisher’s exact tests revealed sexual dimorphism in the nuchal crest and median nuchal line, which is in line with previous studies on sexual dimorphism in the nuchal region. The data suggests that the nuchal crest could be used in sex estimations as early as 15 years, indicating it may be useful for sex estimation in adolescents. However, the absence of dimorphism in occipital shape prevents this element from being considered as a sex indicator.

The Native American Graves Protection and Repatriation Act (NAGPRA) of 1990 mandates all federally funded institutions with legal control over Native American human remains, funerary objects, sacred objects, and objects of cultural patrimony to repatriate those holdings to affiliated descendants. Given the nature of their work, medicolegal institutions are highly likely to meet compliance criteria, but recent research has demonstrated that NAGPRA-awareness in these spaces is very low. This project aims to assess barriers to compliance in medicolegal institutions and, in response, develop best practice guidelines and support materials to assist individuals tasked with NAGPRA in navigating the repatriation process ethically and efficiently. The project also seeks to raise awareness of NAGPRA within the forensic community, highlight its potential utility in addressing forensic public health crises, and position NAGPRA as an opportunity for forensic anthropologists—who are uniquely qualified for this work—to further integrate themselves within medicolegal systems.

Previous studies of saw marks have primarily focused on morphological characteristics and their utility in identifying saws suspected to have been utilized in cases of criminal dismemberment. The present study examined the extent to which metric analysis may be used to correlate saw blades measurements of kerf width. A sample of 56 partially defleshed white-tailed deer (Odocoileus virginianus) limbs were utilized as a proxy for human remains. The partial limbs were cut using a variety of commercially available saws, including 11 manual-powered saws and 5 mechanical-powered saws. A total of 500 false start kerfs (FSKs) were measured using digital calipers. Two experiments were performed, with the first test examining the kerf widths of false starts produced on specimens that were restrained using clamps, while the second test analyzed the kerf widths of false starts produced on minimally restrained specimens. Statistical analysis using Hierarchical Linear Modeling indicated a positive relationship between saw blade width (mm) and minimum kerf width (MKW), with the model estimating that MKWs would increase by 1.61 mm for every millimeter increase in blade width. Results from the models indicated that blade width (p<0.001) and the difference between mechanical- and manual-powered saws (p=0.029) were considered statistically significant. A comparison of MKWs produced using manual-powered saws on unrestrained and restrained bones suggests that restraint condition (p=0.009) is statistically significant. In comparisons of MKWs to blade widths, the average ratio for used saws was 2.7% greater than the average ratio for new saws. The mode of the ratios was approximately 1.4, supporting the general rule that MKW does not exceed 1.5 times saw blade width.

Clandestine burials, the interred human remains of forensic interest, are generally small features located in isolated environments. Typical ground searches can be both time-consuming and dangerous. Thermal remote sensing has been recognized for some time as a possible search strategy for such burials that are in relatively open areas; however, there is a paucity of published research with respect to this application. This project involved image manipulation, the analyses of signatures for "graves" of various depths when compared to an undisturbed background, and the use of image classification techniques to tease out these features. This research demonstrates a relationship between the depth of burial disturbance and the resultant signature. Further, image classification techniques, especially object-oriented algorithms, can be successfully applied to single band thermal imagery. These findings may ultimately decrease burial search times for law enforcement and increase the likelihood of locating clandestine graves.

Postmortem interval (PMI) estimation is a necessary but often difficult task that must completed during a death investigation. The level of difficulty rises as time since death increases, especially with the case of skeletonized remains (long PMI). While challenging, a reliable PMI estimate may be of great importance for investigative direction and cost-savings (e.g. suspect identification, tailoring missing persons searches, non-forensic remains exclusion). Long PMI can be estimated by assessing changes in the organic content of bone (i.e. collagen), which degrades and is lost as the PMI lengthens. Visible-near infrared (VNIR) spectroscopy is one method that can be used for analyzing organic constituents, including proteins, in solid specimens. A 2013 preliminary investigation using a limited number of human cortical bone samples suggested that VNIR spectroscopy could provide a fast, reliable technique for assessing PMI in human skeletal remains. Clear separation was noted between "forensic" and "archaeological" specimen spectra within the near-infrared (NIR) bands. The goal of this research was to develop reliable multivariate classification models that could assign skeletal remains to appropriate PMI classes (e.g. "forensic" and "non-forensic"), based on NIR spectra collected from human cortical bone. Working with a large set of cortical samples (n=341), absorbance spectra were collected with an ASD/PANalytical LabSpec® 4 full range spectrometer. Sample spectra were then randomly assigned to training and test sets, where training set spectra were used to build internally cross-validated models in Camo Unscrambler® X 10.4; external validations of the models were then performed on test set spectra. Selected model algorithms included soft independent modeling of class analogy (SIMCA), linear discriminant analysis on principal components (LDA-PCA), and partial least squares discriminant analysis (PLSDA); an application of support vector machines on principal components (SVM-PCA) was attempted as well. Multivariate classification models were built using both raw and transformed spectra (standard normal variate, Savitzky-Golay) that were collected from the longitudinally cut cortical surfaces (Set A models) and the superficial cortical surface following light grinding (Set B models). SIMCA models were consistently the poorest performers, as were many of the SVM-PCA models; LDA-PCA models were generally the best performers for these data. Transformed-spectra model classification accuracies were generally the same or lower than corresponding raw spectral models. Set A models out-performed Set B counterparts in most cases; Set B models often yielded lower classification accuracy for older forensic and non-forensic spectra. A limited number of Set B transformed-spectra models out-performed the raw model counterparts, suggesting that these transformations may be removing scattering-related noise, leading to improvements in model accuracy. This study suggests that NIR spectroscopy may represent a reliable technique for assessing the PMI of unknown human skeletal remains. Future work will require identifying new sources of remains with established extended PMI values. Broadening the number of spectra collected from older forensic samples would allow for the determination of how many narrower potential PMI classes can be discriminated within the forensic time-frame.

The aim of this study was to establish whether the asymmetry of bilateral elements of the skeleton is useful for the reassociation of paired elements in the analysis of commingled skeletal remains; particularly addressing the forensic scenario of Chilean Human Rights cases. The asymmetry of the appendicular skeleton of the modern adult Chilean population was investigated in its morphological aspect, using both traditional anthropometry and geometric morphometrics. The sample was selected from the Colección Subactual de Santiago, housed in the University of Chile, Santiago, Chile, with N= 131 (69 males and 62 females). The traditional metric analysis of size and the geometric morphometric analysis of shape showed that there was a significant difference between sides in both sexes with a strong component of directional asymmetry. Mean metrics and ranges of asymmetry were established, contributing to the characterization of this population. A method to pair match elements from commingled settings, which is a combination of metric ranges of asymmetry and principal component analysis of shape variables, was created resulting in 95% accuracy when pair matching the humerus, radius, femur and tibia. This constitutes an important contribution to the analysis of shape in forensic contexts due to its strong mathematical component, objectivity and repeatability.