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

Abstract

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.

The applicability of forensic time since death estimation methods for buried bodies in advanced decomposition stages

“…Yet, forensic entomology is considered one of the most accurate ways to determine a minimal postmortem interval even for some later phases of decomposition [6]. Another widely used rapid and simple approach relies upon the grading of gross postmortem changes [7]. Focusing on the progression of decomposition stages as a function of temperature, researchers provided scoring systems to establish minimum and maximum time intervals for decomposition (e.g.…”

Not by the Book: Observations of Delayed Oviposition and Re-Colonization of Human Remains by Blow Flies

“…The TBS method as presented by Megyesi et al [ 52 ] has been assessed in temperate areas, such as South Africa and Hawaii, where the temperatures are relatively consistent throughout the seasons, yielding results that were more consistent than those from geographical regions that experience greater seasonal change [ 72 , 73 ]. For example, in Canada, where there is variable humidity and seasonal temperature extremes, TBS evaluation determined that no human individuals were totally skeletonized in under one year, and tissue rarely mummified [ 74 ].…”

Estimation of the postmortem interval based on the human decomposition process

“…An important reason for this is that real-time human remains are mostly unavailable. A recent study published by Ribéreau-Gayon et al 48 investigates whether the use of photographs gives similar decomposition scoring results as scoring real time remains of pigs. A significant difference was found between real-time scores and photograph scores when using Megyesi's method.…”

“…A significant difference was found between real-time scores and photograph scores when using Megyesi's method. 2,48 The authors reason that this is probably due to the fact that Megyesi's method was made for human remains and not pigs. Keough's method, 49 which was developed for pig remains, showed no significant differences between real-time and photograph scores.…”