The Impact of Drugs on Human Decomposition and the Postmortem Interval: Insect, Scavenger and Microbial Evidence

The purpose of this project is to assess the effects of a range of commonly used drugs (prescribed and over-the-counter medications and illicit substances) taken by human donors before death on three of the primary groups of decomposers – insects/arthropods, scavengers, and decomposer microbes – to determine if end-of-life medical conditions and drugs significantly impact decomposition rates, and thus postmortem interval (PMI) estimations. Studies indicate that most people in the U.S. take at least four prescribed medications, which means that it is likely that any body received as a forensic case will have some amount of toxicological loading, not just overdose cases. Yet the effects of these drugs on decomposition patterns and rates are unknown, leading to unquantifiable errors in our PMI estimates. To address this gap in knowledge, our longitudinal postmortem study will follow a minimum of 100 human donors with known medication histories to determine whether drugs lead to a detectable shift in the behavior and/or physiology of organisms who, directly or indirectly, affect PMI estimation methods. “Drugs” refers to illicit substances as well as prescribed and over-the-counter medications. This project will apply cutting-edge multi-omics techniques commonly used in medicine and the life sciences to conduct both targeted and untargeted metabolic profiling (metabolomics and lipidomics) of blood samples from human donors and the transfer (if any) of drug metabolites to maggots and microbes who feed upon the donor tissues. Targeted tandem analyses will be performed using an UPLC-Quadrupole/Orbitrap Q Exactive MS, and untargeted, global metabolite analyses will be performed using an UPLC- Orbitrap Exactive MS. These techniques will detect drugs, drug metabolites, as well as thousands of other metabolites and biomolecules. Concurrently, bacterial communities of the soil and decomposition fluid samples will be profiled using 16S rRNA amplicon gene library sequencing. One principle advantage of the proposed study is the application of untargeted metabolomics for novel discovery as the donors enrolled in our study will likely have a variety of drugs taken over many days prior to death, creating a plethora of metabolites to characterize. As a result, we will develop the first geography-independent methods of PMI estimation that account for toxicological loading in human tissues and potentially discover new biomarkers of PMI. The results of our study will be disseminated in conference papers and peer-reviewed publications in journals across the science spectrum and a workshop for forensic scientists. This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). CA/NCF