Characterising chemical markers of decomposition to advance death investigations

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Decomposition chemistry is an emerging field of forensic science that studies the degradation pathways in a body postmortem. The biochemical degradation of soft tissue involves the disintegration of cells and the release of lipid, protein, carbohydrate, and nucleic acid products to the environment. Analysis of these by-products using advanced chromatographic and spectroscopic techniques over time has the potential to identify novel organic markers that correlate with the postmortem period. This information can be used by law enforcement and forensic services in death investigations, and to improve training in search and recovery techniques (e.g. cadaver dogs). However, current application of these methods in Canadian environments is not possible as chemical data has only been collected using pig carcasses, and recent research has shown that they are not directly comparable to human cadavers. Studies that have utilised cadavers in milder regions of the USA and Australia cannot be applied to Canadian environments due to fundamental differences in climate and biogeography. This research aims to characterize the unique chemical changes that occur during soft tissue decomposition and to determine the impact of the eastern Canadian climate on the rate and process of decay. Research will be conducted at the Secure Site for Research in Thanatology (SSRT), the only facility in Canada for the study of human decomposition using donated cadavers. Organic samples collected at SSRT will be analysed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry, the only instrument with sufficient resolution to separate and identify the complex products of decomposition. The program involves the systematic collection of volatile organic compounds (VOC) from air and soil to develop a comprehensive decomposition odour database. The database will be used to discover the key VOCs used by cadaver dogs for locating victim remains in a cold climate. Samples of tissue, soil and textiles will be collected to extract and identify chemical markers of decomposition that correlate with the postmortem period. Characterisation of these markers will allow for more accurate estimations of time since death or deposition of a body. The research will change our understanding of how cadaver dogs locate decomposition odour in Canada and will be used to improve their training and success in locating victim remains. Identification of novel decomposition markers are essential for providing accurate timeframes to law enforcement and will aid victim identification by narrowing pertinent missing persons records. The fundamental knowledge gained from this program will set a global standard for the decomposition chemistry research community. The outcomes have a clear benefit to both law enforcement and families of victims in Canada, as well as global implications through the rapid identification and repatriation of victims of war crimes or mass disasters.