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Studies assessing the use of ground-penetrating radar (GPR) for locating unmarked human graves commonly use pigs as proxies, with recent concerns about the adequacy of pigs as substitutes for humans. Also, there is little agreement on how to identify and describe GPR signals associated with graves. Hence, this project's aim is to compare GPR signals acquired over simulated clandestine graves with pig and human remains. We established human, pig, and control graves at the REST[ES] human decomposition facility in May 2022 and monitored the graves over 17 months using a 250 MHz antenna GPR system. Our results showed the presence of perturbed and V-shaped reflectors, diffraction hyperbolas, and reflectors with amplitude loss at depth between 0.6 and 0.75 m in the radargram for graves with human and pig remains. We corroborate recent studies which concluded that the use of proxies is a viable alternative to human cadavers. The observed radar signatures were classified into five key patterns, which are characteristic of similar data collected with 250 MHz above graves reported in the literature. These classes are: V-shaped dipping reflections from grave walls (class A), small hyperbolic reflections superimposed onto a near-linear reflector (class B), hyperbolic reflections from remains within the grave (class C), new high-amplitude reflection patterns (class D) and significant loss or interruption of reflections (class E). Our proposed classification can help streamline future investigations where the goal is to interpret burials within large GPR datasets and provide language to communicate these results to the broader scientific community.

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Decomposition studies have been conducted in several regions of the world, but relatively few have investigated taphonomy in tropical environments. Even fewer have explored carcass decomposition during multiple tropical seasons, leaving the relationships between season and decomposition in tropical environments poorly understood. Ten decomposition studies using 30 carcasses were conducted in Honolulu, Hawaii, USA to start addressing this knowledge gap. These studies show that some postmortem processes were observed regardless of season. Carcass temperature and chemistry were spatiotemporally variable. Fly larval masses were consistently observed within 3 days (∼75 ADD) postmortem and carcasses lost 60%-90% of mass by 10 days (∼250 ADD) postmortem (Total Body Score ∼26). Season had a significant effect on decomposition, yet the warmest and most humid seasons did not always result in the most rapid and extensive decomposition. Seasonal variation appears to be less pronounced than at other tropical decomposition sites.

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The published literature shows a lack of methods to evaluate the patterns and extent of decomposition of human remains and to estimate the post-mortem interval (PMI) in humid, continental (Dfb) climates such as Quebec. The aim of this study was to address this gap in the current knowledge base by providing the first observations from human corpses studied under controlled conditions in Quebec. A 12-month study was conducted at the site for Research in Experimental and Social Thanatology; the first human taphonomy facility in Canada. Six human donors with known time of death were deposited across spring (n = 1), summer (n = 3), and autumn (n = 2) 2021. The lack of suitability of the total body score method to evaluate the extent of decomposition at the facility prompted the development of a new scoring system based on the macromorphoscopic changes observed. The scoring system was applied to the donors to evaluate decomposition throughout seasons. All donors followed comparable decomposition trajectories, regardless of the season of deposition. Eighty-five percent of taphonomic patterns appeared in the first 25 experimental days or 5000 Kelvin accumulated degree days (350 ADD). Extensive desiccation of tissues was observed at a median of 21 experimental days across donors, resulting in a plateau within decomposition with no extensive skeletonization. To the authors' knowledge, this is the first published report of experimentally observed desiccation in such a form in a Dfb climate. This study provides new data on the types of decomposition patterns to expect in forensic investigations in southern Quebec and comparable climates.

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In the context of increased scrutiny of the methods in forensic sciences, it is essential to ensure that the approaches used in forensic taphonomy to measure decomposition and estimate the postmortem interval are underpinned by robust evidence-based data. Digital photographs are an important source of documentation in forensic taphonomic investigations but the suitability of the current approaches for photographs, rather than real-time remains, is poorly studied which can undermine accurate forensic conclusions. The present study aimed to investigate the suitability of 2D colour digital photographs for evaluating decomposition of exposed human analogues (Sus scrofa domesticus) in a tropical savanna environment (Hawaii), using two published scoring methods; Megyesi et al., 2005 and Keough et al., 2017. It was found that there were significant differences between the real-time and photograph decomposition scores when the Megyesi et al. method was used. However, the Keough et al. method applied to photographs reflected real-time decomposition more closely and thus appears more suitable to evaluate pig decomposition from 2D photographs. The findings indicate that the type of scoring method used has a significant impact on the ability to accurately evaluate the decomposition of exposed pig carcasses from photographs. It was further identified that photographic taphonomic analysis can reach high inter-observer reproducibility. These novel findings are of significant importance for the forensic sciences as they highlight the potential for high quality photograph coverage to provide useful complementary information for the forensic taphonomic investigation. New recommendations to develop robust transparent approaches adapted to photographs in forensic taphonomy are suggested based on these findings.

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The feeding patterns of species of large sharks on human corpses are well documented in the literature however, that of smaller sharks are less known. This may introduce uncertainty in the medicolegal conclusions. For that reason, accurate identification of patterns of shark predation is very relevant, specifically in areas bordered by the sea. In the case described here, an unidentified lesion was noted on the body of a victim of a scuba diving accident off the island of Kauai, in Hawaii. The aim of this study was to identify the origin of the lesion and investigate its potential to inform on the context of death and/or decomposition. The original outline of the lesion was digitally reconstructed to enable the collection of measurements which were compared with the literature and interpreted with an interdisciplinary approach. This approach permitted to determine that the macroscopic appearance and dimensions of the lesion (major axis = 3.53 cm) were consistent with a bitemark of a cookiecutter shark (Isistius brasiliensis). It was further determined that the bitemark was incomplete and that the specimen involved had a total length of about 24 cm and was likely to be a juvenile. This is the second report in the published literature of cookiecutter bitemarks on humans in the Hawaiian waters. This study brings new evidence-based insights into the interactions between cookiecutter sharks and human remains in marine environments and provides a valuable contribution to the knowledge base on the topic.

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Accurate determination of the origin and timing of trauma is key in medicolegal investigations when the cause and manner of death are unknown. However, distinction between criminal and accidental perimortem trauma and postmortem modifications can be challenging when facing unidentified trauma. Postmortem examination of the immersed victims of the Yemenia airplane crash (Comoros, 2009) demonstrated the challenges in diagnosing extensive unusual circular lesions found on the corpses. The objective of this study was to identify the origin and timing of occurrence (peri- or postmortem) of the lesions.A retrospective multidisciplinary study using autopsy reports (n = 113) and postmortem digital photos (n = 3 579) was conducted. Of the 113 victims recovered from the crash, 62 (54.9 %) presented unusual lesions (n = 560) with a median number of 7 (IQR 3 ∼ 13) and a maximum of 27 per corpse. The majority of lesions were elliptic (58 %) and had an area smaller than 10 cm2 (82.1 %). Some lesions (6.8 %) also showed clear tooth notches on their edges. These findings identified most of the lesions as consistent with postmortem bite marks from cookiecutter sharks (Isistius spp.). It suggests that cookiecutter sharks were important agents in the degradation of the corpses and thus introduced potential cognitive bias in the research of the cause and manner of death. A novel set of evidence-based identification criteria for cookiecutter bite marks on human bodies is developed to facilitate more accurate medicolegal diagnosis of cookiecutter bites.

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