The Postmortem Interval: A Systematic Study of Pig Decomposition in West Central Montana

Hillary Renee' Parsons, The University of Montana

Abstract

The postmortem interval (PMI) is an important piece of information used by forensic and criminal investigators to help investigate crimes and other unattended deaths. Time since death estimations assist law enforcement in providing a reference with which to compare a suspects alibi, identify victims of crime, and solve cases. Studies of decomposition have been conducted at the University of Tennessee’s Anthropological Research Facility in Knoxville, TN; however, decomposition at high altitude climates characterized by colder temperatures and arid conditions is poorly understood. Further, the lack of postmortem interval studies in west central Montana has hindered the investigation and identification of recovered individuals in our area. Using pigs as proxies for human cadavers, the goal is to observe the rates of decomposition to help estimate the postmortem interval. This project provides information on how the rate of decomposition of two pigs is affected by the climate and insect activity of west central Montana in August and October; late summer and early fall, respectively. The unique climate of west central Montana produces slower decomposition rates that differ significantly from those observed in Tennessee and elsewhere in the United States. The use of accumulated degree-days (ADD) to estimate the postmortem interval reveals accurate time since death estimations and consistency with previous PMI studies despite significant differences in climate and weather patterns. This project is the first of a series of decomposition research projects that UM master and doctoral student in the anthropology department will conduct in order to systematically document the process of decomposition in west central Montana.