Using Accumulated Degree-Days to Estimate the Postmortem Interval from Decomposed Human Remains

TLDR

Forensic anthropologists rely on the state of decomposition to estimate postmortem interval, treating decomposition as a semi‑continuous variable in combination with accumulated‑degree‑days. The study aims to improve PMI estimates by scoring decomposition with a point‑based system that incorporates accumulated temperature (ADD). The authors scored 68 known‑death cases for decomposition and derived a regression equation linking decomposition score to accumulated‑degree‑days. The regression shows that accumulated‑degree‑days explain about 80 % of decomposition variation, confirming that decomposition depends on accumulated temperature rather than elapsed time alone.

Abstract

Forensic anthropologists often rely on the state of decomposition to estimate the postmortem interval (PMI) in a human remains case. The state of decomposition can provide much information about the PMI, especially when decomposition is treated as a semi-continuous variable and used in conjunction with accumulated-degree-days (ADD). This preliminary study demonstrates a supplemental method of determining the PMI based on scoring decomposition using a point-based system and taking into account temperatures in which the remains were exposed. This project was designed to examine the ways that forensic anthropologists could improve their PMI estimates based on decomposition by using a more quantitative approach. A total of 68 human remains cases with a known date of death were scored for decomposition and a regression equation was calculated to predict ADD from decomposition score. ADD accounts for approximately 80% of the variation in decomposition. This study indicates that decomposition is best modeled as dependent on accumulated temperature, not just time.