A Simplified Approach to Understanding Body Cooling Behavior and Estimating the Postmortem Interval

Abstract

Ascertaining the postmortem interval or PMI has been an item of interest over many decades in forensic science for crime scene investigations. The challenge revolves around establishing the postmortem interval or PMI with a single temperature measurement, given the known initial and the final boundary condition of a human body and room temperature. Despite the advent of a succession of single, double, and triple-exponential analytical models, and more recently, the 3-D heat-transfer modeling, the uncertainty remains in the PMI estimation. This study presents a pragmatic way to solve this problem in a two-step approach. First, we attempted to understand the cooling rate in various body parts. Second, we proposed a hyperbolic modeling approach to fit the time-dependent temperature data to estimate the PMI. The latest digital data of Wilk et al.’s study provided the platform for validating our solution approach. Overall, the use of 20 subsets of three bodies involving Wilk et al. and five from one body of Bartgis et al. provided the required data. Although body imaging and 3-D modeling greatly facilitate our understanding of overall body-cooling behavior in the modern era in real-time, a simple semi-analytical tool can corroborate the model results for PMI.