Evaluation of decomposition residual odor using Sus scrofa as a sampling model
Raymer, Jennifer L.
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This research project will impact the forensic field by providing an insightful scientific perspective on the chemical composition of decomposition odors of human analogues emitted into the environment. By studying the chemical makeup of decomposition odor or the “scent of death”, enhanced understanding of stage-specific volatile organic compounds (VOCs) can provide better understanding for better detection methods to be developed. This study also achieved a preliminary understanding of when a specific area can be cleared of any remaining decomposition odor. Not only will this study aid in the potential location of holding sites or transportation methods, it will also aid in optimal training of human remains detection dogs. There has been limited scientific research into how decomposition residual volatile organic compounds change over time, with even less scientific research into how the compounds change in a dry, arid environment such as west Texas. Emerging research has begun to look into the compounds present in soil during decomposition, but limited studies are specifically looking at the change of compounds as a longitudinal analysis over time, after the removal of the decomposing item. The purpose of this study was to monitor and provide abundances of the target decomposition odor vapors emanating from the soil after removal of decomposing human analogues (sus Scrofa). Pig meat samples and carcasses were placed in an outdoor study site to model the decomposition process and VOCs were collected intermittently over a one-month period. The odor collection process consisted of allowing pigs to decompose for a period of 14 days, 17 days and 21 days, then removing the pigs and sampling the soil once per week for a period of four weeks. Instrumental analysis utilized Divinylbenzene/Carbon/Polydimethylsiloxane (DVB/CAR/PDMS) coated Solid Phase-Microextraction (SPME) fibers that were injected into a Gas Chromatography-mass Spectrometry (GC-MS) system for the identification of extracted soil headspace odor profiles of target decomposition odors. The soil samples were sampled individually in 15mL glass vials for a period of 24 hours to allow for headspace extraction time optimization. Weather conditions such as temperature and humidity were recorded during each soil sample collection, as well as soil pH and moisture content. During each sample extraction, at each of the three intervals, both abundance and type of target volatiles were analyzed. The purpose was to document the change in both the type of volatiles present and their abundance at each of the set intervals. VOCs of interest were identified over the duration of the study, showing distinctive trends in compound abundance and disappearance. The benefit produced by the study has heightened the understanding of how decomposition odor changes over a set period of time. This research will ultimately aid in the knowledge and understanding of odor composition and concentration levels of residual decomposition odor for given decomposition times, with the generated information supporting search and recovery of holding sites and possible modes of transportation at various stages of decomposition.