Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Advisor

Harman, Melinda K

Committee Member

Weisensee , Katherine E

Committee Member

Mikhailova , Elena A

Abstract

The Postmortem Interval (PMI) is the amount of time between the death of an individual and the discovery of the remains. Existing forensic techniques for the determination of the PMI are limited once soft tissue fully decays [31, 32]. A novel technique has recently been developed using the molecule Citrate (C6H8O7) to calculate the Postmortem Interval (PMI) [26]. Currently, this method cannot be practically applied due to the limited understanding of different forensic environments on the biochemistry of postmortem bone. In addition, further understanding of bone citrate measurement methods is needed to determine a practical field measurement approach. This study aims to (1) identify alternative measurement methods for bone citrate and (2) design a bioreactor system that can discretize the myriad of environmental variables that impact decomposition. Using a colorimetric assay and high-performance liquid chromatography (HPLC), this study measured bone citrate concentrations at 1.26 and 1.39 wt. % (colorimetric assay measurement) and 1.69 wt. % (HPLC measurement). Compared to the value established by Schwarcz et al. (2013) of 2.0 wt. %, results show 63 %, 69 %, (colorimetric assay measurement) and 85 % (HPLC measurement) extraction and recovery of citrate. However, high standard deviations and intra-sample variance suggest a need for further analysis of the sample preparation methods, as well as assessment of potential techniques for the quantification of citrate concentration. Forensic bioreactors were designed based on forensically-relevant environmental variables discretized using the following soil science metrics: soil temperature regime, soil moisture regime, slope, texture, soil horizon, cation exchange capacity, soil pH, and organic matter content. A total of fourteen different environmental conditions were created and controlled successfully over a 60 day experiment. Results demonstrate successful development, implementation and control of forensic bioreactors. A pilot study demonstrates the need for further refinement of chemical methods; however, porcine rib bone samples were successfully aged in bioreactors over 60 days. This research demonstrates the need for further development of the citrate chemical analysis to ensure accurate field testing. Once a field method for citrate measurement has been established, bioreactor systems can be created to replicate many different of clandestine burial contexts, which will allow for the more rapid understanding of environmental effects on skeletal remains. Ultimately, through the use of forensic bioreactors, global research can be piloted in the local laboratory.

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