Effects of Ground Temperature, Ground Material Properties and Body Position on Postmortem Axial Heat Transfer

The effects of body position, ground temperature and ground material properties on postmortem axial heat transfer were investigated to inform numerical death-time estimation procedures. A postmortem cooling simulation in unforced convection conditions with no ground contact served as the control. Postmortem cooling was simulated in the supine position on a modelled cold concrete floor and on a domestic-type heated floor. Permanent axial displacement of the antemortem central isotherm (ACI) and postmortem central isotherms (PCI) away from the cold concrete ground and towards the heated floor was observed due to the supine body position. Both ground types absorbed heat from the body and were not infinite heat sinks. The postmortem temperature plateau (PMTP) was significantly shortened by both ground types, being shortest on the heated floor. Legacy methods of death-time estimation based on single-point (rectal) thermometry cannot detect ACI/PCI displacement that determines the measured core temperature value. They are based on the supine position and do not apply corrective factors for ground-associated variables or non-supine positions. All these constitute sources of uncertainty. Realistic modelling of body position and ground-associated thermophysical variables is essential to correctly account for their effects during postmortem cooling, and use of the novel multipoint axial thermometry (MAT) protocol of death-time estimation, which can detect ACI/PCI displacement and simulate body position and pose, is advocated for this.