A preliminary examination of differential decomposition patterns in mass graves

This study represents a preliminary, quantitative approach to the examination of differential decomposition patterns in mass graves. Five pairs of mass graves, each containing the carcasses of 21 rabbits, were used to examine decomposition rates at four fixed positions within the burial. A pair of graves was exhumed at approximately 100 accumulated degree day (ADD) intervals. At exhumation the total body score (TBS) and internal carcass temperature of each rabbit were recorded. Although there was no significant difference between decomposition rates for core and deep-positioned carcasses (p = 0.13), all other position differences were significant (p < 0.001). Decomposition occurred fastest in shallow carcasses, followed by mid-outer carcasses; both deep and core carcasses exhibited a slower rate. Internal carcass temperature was significantly influenced by carcass location within the mass grave; there was a mean internal temperature difference of ca. 1 oC between deep and shallow carcasses (30 cm apart). Adipocere formation was minimal and confined, with the exception of a single individual in the mid- periphery, to the deepest level. Decomposition rate may be as affected by the compactness of a mass as by interment depth and/or peripheral substrate contact, and further investigation into the role of oxygenation and pH are required

Preliminary soilwater conductivity analysis to date clandestine burials of homicide victims

This study reports on a new geoscientific method to estimate the post-burial interval (PBI) and potential post-mortem interval (PMI) date of homicide victims in clandestine graves by measuring decomposition fluid conductivities. Establishing PBI/PMI dates may be critical for forensic investigators to establish time-lines to link or indeed rule out suspects to a crime. Regular in situ soilwater analysis from a simulated clandestine grave (which contained a domestic buried pig carcass) in a semi-rural environment had significantly elevated conductivity measurements when compared to background values. A temporal rapid increase of the conductivity of burial fluids was observed until one-year post-burial, after this values slowly increased until two years (end of the current study period). Conversion of x-axis from post-burial days to 'accumulated degree days' (ADDs) corrected for both local temperature variations and associated depth of burial and resulted in an improved fit for multiple linear regression analyses. ADD correction also allowed comparison with a previous conductivity grave study on a different site with a different soil type and environment; this showed comparable results with a similar trend observed. A separate simulated discovered burial had a conductivity estimated PBI date that showed 12% error from its actual burial date. Research is also applicable in examining illegal animal burials; time of burial and waste deposition. Further research is required to extend the monitoring period, to use human cadavers and to repeat this with other soil types and depositional environments

Investigating Variation in the Prevalence of Weathering in Faunal Assemblages in the UK: A Multivariate Statistical Approach

This article presents an exploratory multivariate statistical approach to gaining a more comprehensive understanding of variation in subaerial bone weathering in a British context. Weathering is among the most common taphonomic modifications and provides a crucial line of evidence for reconstructing the taphonomic trajectories of faunal assemblages and archaeological deposits. It provides clear evidence for prolonged subaerial exposure either before deposition in a context or because of later disturbance. In combination with other taphonomic indices such as gnawing, trampling, abrasion and fracture patterns, weathering can be used to reconstruct depositional histories and to investigate the structured treatment of different body parts or taxa in deposition. However, a broad range of factors affect the prevalence and severity of weathering, and therefore patterns can rarely be interpreted at face value. Many variables such as predepositional microenvironment cannot be traced archaeologically. Other contributory factors pertaining to the structural properties of elements and taxa can be discerned and must be taken into account in interpreting weathering signatures. However, disagreement exists regarding which variables are most important in mediating weathering. In addition for zooarchaeologists to interpret modification patterns, it is necessary for elements and taxa that are most likely to be affected by weathering to be defined. This is the case as deposits that are dominated by those classes of remains are likely to exhibit greater modification than those that are not, even if depositional histories were similar. Through a combination of classification tree and ordinal regression analysis, this article identifies which archaeologically recoverable variables explain the greatest variance in weathering and which anatomical elements and taxa are most likely to be affected in archaeological deposits in the UK

Pig Tales: Forensic Taphonomy in Cozine Creek

The medicolegal community relies heavily upon determining the postmortem interval (PMI), the knowledge of how much time has elapsed since the person has died. Forensic taphonomy is the study of postmortem changes caused by outdoor environmental conditions that play a crucial role in decomposition rates. These include local temperatures, humidity, soil, plants, and insect and other scavenger activity. Minimal research exists examining the rate of surface decomposition in the Pacific Northwest climate. The purpose of this pilot study is to analyze the rate of decomposition in the microclimate of McMinnville, Oregon. A deceased juvenile pig (Sus scrofa) was placed in a secure cage in Cozine Creek on February 17, 2019. Data collection continues until May 2019 and includes daily observations, photographs, weather data, and insect collection for entomological assessment. Statistical analysis will be performed once all data is collected. Preliminary results suggest weather fluctuations and insect activity significantly influence decomposition rates. During the first four weeks, cold weather conditions did not favor decomposition: snow, low temperatures, and few insects. Once temperatures reached 13℃, a dramatic increase in insect activity and intensity was observed. Dermestid beetles, maggot masses, and blowflies were present, and within days a substantial increase in decomposition occurred

Bone modification and the conceptual relationship between humans and animals in Iron Age Wessex

archaeological records. As a result of the manner in which human and animal remains are traditionally studied and reported on, the analysis of taphonomic processes which affect the character of specimens between death and incorporation into forming deposits is often confined to butchery, burning and fragmentation. This paper argues that current methods of osteoarchaeological analysis fail to recognise the potential of a substantial and easily accessible source of information in paying little attention to the processes of weathering, gnawing, trampling, abrasion and longitudinal/spiral fracturing. More detailed taphonomic assessments have tended to focus on one specific process to answer a particular research question rather than taking a holistic approach to pre-depositional affects (e.g. Outram 2001). Consequently biographies of skeletal material are only partially complete, as the period in the material existence of bone prior to subterranean deposition is not fully investigated. The aforementioned taphonomic processes can provide substantial evidence for human decision making regarding the treatment of different classes of remains. This research explores the potential of holistic taphonomic analysis in a sample of c.9500 human and faunal specimens from the Iron Age sites of Winnall Down and Danebury. These sites were selected as they are located in the heart of Wessex, an area about which there has been considerable discourse and disagreement regarding the nature of human and animal bone treatment in the Iron Age. Through comprehensive taphonomic analysis, highly regulated, socially circumscribed behaviours surrounding bone handling were revealed. These results are suggestive of separate practices relating to the treatment of human and faunal remains with the latter exhibiting significantly greater evidence of exposure. The analysis of bone modification in features containing both human and faunal remains reveals a blurring of the boundary between human and animal identities, as the treatment of the two classes of material differs to a significantly lesser degree than when analysing the entire assemblage. Therefore each class of material is subjected to a more closely related mode of treatment. This might be seen as indicative of a conceptual proximity of human and faunal remains

Forensic Science for Cambodian Justice

Cambodia is universally associated with its killing fields – a horrific inheritance from the Khmer Rouge era. Whilst mass grave evidence from that era is referred to in history and social science publications on Cambodia, it has not featured in a legal context to date. The establishment of the Extraordinary Chambers in the Courts of Cambodia (ECCC) creates an opportunity for a review of this evidence 30 years after the events. Those alleged to be accountable for Cambodia’s killing fields are finally being brought to justice. The question is whether this will occur with or without forensic science evidence from the mass graves. This article explores the reasons for using forensic science in the Cambodian context and outlines its potential for legal proceedings. Drawing on relevant literature in the forensic and legal areas, the article provides a brief outline of the legal context created by the ECCC and examines various projects that have recorded evidence relating to the mass graves. Employing an analysis of semistructured, in-depth interviews with forensic and legal experts as well as representatives from the ECCC and the Documentation Center of Cambodia (DC-Cam), the article explores the value of forensic science for the ECCC, including its impact on humanitarian issues in Cambodia

The suitability of visual taphonomic methods for digital photographs: An experimental approach with pig carcasses in a tropical climate

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