Towards a more accurate estimation of the time since death in human bodies found decomposed in Australian conditions

Abstract

The fate of the human body after death is a subject that has fascinated enquirers, both religious and scientific, for millennia. However, objective research into the causes and nature of human decomposition has only taken place in the last two centuries and quantitative measurement of the process as a means of estimating the time since death has only recently been attempted. Most research has involved attempting to estimate the time since death (TSD) in the early period after death; from the moment of death until the body cools to ambient temperature. When this phase is past and the body begins to putrefy, the estimation of the time of death becomes increasingly more difficult. The primary aim of this thesis is to develop a practical and easily applicable method for estimating the time since death (TSD) in the first two weeks of the post-mortem interval. A substantive discussion of the literature on the TSD in the early (up to 48 hour) post-mortem interval and the putrefaction period through to skeletonisation will put into context the aims and methodology employed in this research. The chief methodological approach is retrospective, with the addition of practical and experimentally based observations to increase the accuracy of and test the statistical modelling of time since death. The experimental format followed included: (1) Accessing the Australian National Coroner's information System (NCIS); (2) Collating data on individual autopsies of persons who had died some time prior to discovery and in whom the time since death was known with reasonable certainty; (3) Developing a quantitative method of assessing the degree of decomposition in a number of specific body organs and from this data compiling a numerically summated total body score (TBS) for each individual; (4) Increasing the accuracy of this system by attending a series of autopsies at the Victorian Institute of Forensic Medicine; (5) Further controlled research into human decomposition at the Forensic Anthropology Research Center ('body farm') of Texas State University in order to assess the role of temperature in the rate and process of decomposition; (6) Using the resultant dataset along with a range of environmental variables to develop a series of mathematical models to estimate time since death based on the degree of decomposition; (7) Testing the accuracy of the models both statistically and practically on a series of cases that were not involved in developing the time since death models. Models resulting from this work indicate that an accurate TSD in Australian indoor conditions can be estimated using the TBS independent of humidity and temperature variables.