Sharp and blunt force trauma concealment by thermal alteration in homicides: An in-vitro experiment for methodology and protocol development in forensic anthropological analysis of burnt bones

Abstract

Burning of human remains is one method used by perpetrators to conceal fatal trauma and expert opinions regarding the degree of skeletal evidence concealment are often disparate. This experiment aimed to reduce this incongruence in forensic anthropological interpretation of burned human remains and implicitly contribute to the development of research methodologies sufficiently robust to withstand forensic scrutiny in the courtroom. We have tested the influence of thermal alteration on pre-existing sharp and blunt trauma on twenty juvenile sheep radii in the laboratory using an automated impact testing system and an electric furnace. The testing conditions simulated a worst-case scenario where remains with pre-existing sharp or blunt trauma were exposed to burning with an intentional vehicular fire scenario in mind. All impact parameters as well as the burning conditions were based on those most commonly encountered in forensic cases and maintained constant throughout the experiment. The results have shown that signatures associated with sharp and blunt force trauma were not masked by heat exposure and highlights the potential for future standardization of fracture analysis in burned bone. Our results further emphasize the recommendation given by other experts on handling, processing and recording burned remains at the crime scene and mortuary.

Knife cut marks inflicted by different blade types and the changes induced by heat: a dimensional and morphological study

“…Previous literature showed that sharp force trauma on a bone could survive the bone being burned [26, 32-34, 38, 59]. It is highlighted that morphological changes to the trauma could occur because of the burning; hence, further research is necessary [30,[32][33][34][35][36]. Similarly, all the cut marks in this study were grossly identifiable after burning, despite the bone sample fracturing, with a small number of fractures intersecting cut marks.…”

“…Defined by location and direction of fracture propagation, heat-induced fractures can be categorised as longitudinal, transverse, curved transverse, delamination, and patina [32]. Heat-induced fractures and fragmentation can be recognisable, but they may be confused also with skeletal perimortem trauma because their features mimic or obscure antecedent traumatic characteristics [32][33][34].…”

“…Recently, studies on the effects of burning on the identification of cut marks have become more prevalent in the forensic literature. Previous studies have shown that cut marks in burned bones remain identifiable and how each mark can be differentiated from heat-induced fractures of the bone [32][33][34][36][37][38]. However, despite surviving the burning process, the heat can modify the characteristics of cut marks in the bone.…”

“…Various analytical methods have been used to examine the morphology of sharp-inflicted trauma on unburnt and burnt bones. Microscopic methods, such as stereomicroscopy and scanning electron microscopy, are the most commonly employed [27,32,33,35,36,[38][39][40][41].…”

An assessment of the reliability of cut surface characteristics to distinguish between hand‐powered reciprocating saw blades in cases of experimental dismemberment

“…All specimens were macerated on the same day of purchase in the UCL Bioarchaeology Laboratory utilizing manual de‐fleshing and hot water enzyme maceration [27,28]. In an attempt to enhance experimental replicability [29] specimens were macerated prior to sectioning. Defleshed porcine bones have previously been used in tool mark analysis research [13,21,30].…”