A Biochemical Investigation of Buried Remains in Contrasting Soil Types in Southern Ontario.

Following the detection of a clandestine grave containing a carcass, collection of tissue samples is important for the estimation of the post burial interval (PBI). Throughout the decomposition process of a carcass, adipose tissue is subjected to hydrolytic enzymes that convert triacylglycerides (TAG) to their corresponding unsaturated, saturated and salts of fatty acids. The composition of fatty acids in the decomposed tissue will vary with the post mortem period, but it is unknown what affect the soil type has on lipid degradation. Domestic pig (Sus scrofa) carcasses were clothed in 100% cotton t-shirts and 50% cotton/50% polyester briefs, and buried at a consistent depth at three field sites of contrasting soil type (silty clay loam, fine sand and fine sandy loam) in southern Ontario. Fatty acid analysis of tissue samples, exhumed at two, eleven and fourteen month post burial intervals, was conducted using Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy and Gas Chromatography – Mass Spectrometry (GC-MS). DRIFT spectroscopy analysis of the tissue samples provided a qualitative profile of lipid degradation. GC-MS was used to quantify the relative concentrations of myristic (14:0), palmitic (16:0), palmitoleic (16:1), stearic (18:0) and oleic (18:1) acids. Analysis revealed that the relative concentration of the unsaturated fatty acids decreased, while the saturated fatty acids increased as decomposition proceeded. The results of this study will be presented, and the potential for fatty acid analysis to be incorporated into methods for the estimation of PBI will be discussed.

 Key Words: forensic science, fatty acid, gas chromatography – mass spectrometry (GC-MS), infrared spectroscopy