Chemical trace XRF analysis to detect sharp force trauma in fresh and burned bone

Forensic anthropologists may not always be able to differentiate heat-induced fractures from fractures with other aetiologies, namely sharp force traumas, with clear nefarious impact on medico-legal conclusions. The objective of this study was to experimentally investigate if blade chemical traces are transferred to defleshed bone tissue and if they remain there after a burning event. This was accomplished by prompting sharp force traumas in 20 macerated fresh pig ribs with five different instruments, namely a stainless steel knife, an artisanal knife and a ceramic kitchen knife, a small axe and a large axe. Another pig rib was used as control, not being subjected to any trauma. All instruments were probed by X-ray fluorescence (XRF) to establish the composition of each blade. Bone samples, both pre-burned and post-burned (at 500 °C, 700 °C, 900 °C and 1100 °C), were then probed by XRF. All sharp force instruments left detectable chemical traces on pre-burned bone, although not in all samples. Furthermore, traces were still detected after experimental burning in most cases. Potentially, XRF can provide relevant information about the aetiology of fractures in burned and unburned bones, although the effect of soft tissues and diagenesis must still be investigated.