Cut or burnt? - Categorizing morphological characteristics of heat-induced fractures and sharp force trauma

Distinguishing trauma from heat-induced fractures is a challenge faced by forensic anthropologists and pathologists during medicolegal investigations in which fire has been used by the perpetrators to destroy evidence. This paper aims to validate the provided identification features to distinguish between fire induced alterations and sharp force trauma. A total of 80 cremated adult individuals were used in this paper: 3 recently deceased embalmed cadavers from Cementerio Sur de Madrid for the sharp force trauma experiment in which 55 pre-burning injuries were inflicted using a machete and a serrated knife in different anatomical regions. And 77 cremated individuals from the Forensic Anthropology and Odontology Laboratory osteological collection. Five cremated long bones from this collection were selected, and 10 cuts were manually inflicted using a serrated knife to analyse post-burning trauma. Heat-induced changes and trauma morphologic characteristics were thus documented and analysed. The examination and documentation of morphological traits enabled the production of a heat-induced changes visual guide and a flow-chart. Two intraclass correlation tests were performed to validate the capacity of the observer to distinguish between fire related alterations and toolmarks. The results obtained in the statistical analysis indicate that, even if the toolmarks are visible and recognizable upon macroscopic observation by the observers, some features, such as the step and the transverse fractures can be mistaken with inflicted trauma. The use of the proposed features coupled with careful anthropological examination is recommended and has been found functional for participants with no prior knowledge in the analysis of cremated remains.