Predictive Equation Model to Estimate Postmortem Interval using Total Body Score

Abstract

The decomposition process of corpse varies due to many factors. There are several studies conducted to improvethe postmortem interval (PMI) by visual inspection of human remains. In this study, a total body scoring methodwas developed to estimate the PMI based on the decomposition and degree days (DD). One hundred and threecases were used to estimate the PMI. The autopsy reports were scored using the decomposition scoring method. Thetemperature data was obtained from the Thailand Meteorology Department (TMD). The PMI was estimated usingthe total body score (TBS), accumulated degree day (ADD) and accumulated degree hour (ADH) from the findingdate back until the predicted time since death. To this end, a retroactive approach was taken in which cases from themedical examiner with a known “date last seen” and “date recovered” were compiled. A qualitative analysis wasconducted examining the specific decomposition changes which occur in various contexts. Quantitatively, a linearregression analysis was employed to determine if DD or TBS explained more of the variation in decomposition.The ADH, ADD and TBS were determined to be the main components in modelling decay. These results suggestthat the TBS can be optimally used to assess PMI. While the ADD and ADH were used to overestimate PMI, whichindicating inconsistency of the method. In total, a set of time since death estimation formula applicable to indoor,outdoor, and aquatic contexts was produced, and region-specific standards best suited to estimating time sincedeath in Thailand. Due to the subjectivity in all the available methods and decomposition is a highly variableprocess. Further research is required before an estimated PMI should be considered as evidence in court.