This final research report provides a discussion of the research design on a project to examine microenvironmental factors on decomposition.
The authors of this final research report discuss a longitudinal study of human donors with known disease and drug histories; the researchers performed a series of trials with multiple donors placed simultaneously in the same outdoor microenvironment so that differential decomposition could be observed. The purpose of the study was to systematically examine if and how a body exerts agency over its own decomposition process by studying the effects of drugs, including prescription medications, and end-of-life diseases on decomposition rates and patterns; to determine if and how postmortem interval (PMI) estimates should be modified when certain drugs are present; and to assess the need to perform toxicological testing prior to PMI estimation. The research study specifically examined whether drugs and their metabolic products have an impact on the physiology, behavior, or community composition on the three primary types of decomposers: insects, scavengers, and microbes. The authors applied multi-omics approaches to determine whether drugs lead to a detectable shift in the metabolome and microbiome of human donors that would impact the behavior and/or physiology of organisms that use the human body as a food source. In the results section, the authors discuss donor disease load and toxicological screening; toxicological screening across matrices; decomposer effects including soil chemistry and microbial ecology, insect activity, and scavengers; and the impact on decomposition rates and PMI, including microbial ecology, entomological methods of PMI estimation, and morphological PMI methods—total body score. The authors found thousands of drug-related metabolites among 22 donors that transferred to decomposer matrices, and some of those metabolites may be important biomarkers of decomposition; the inter-donor variability based on intrinsic factors exists and highlights a need to further investigate the effects of intrinsic traits on decomposition process since they have an effect on PMI estimates.