The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Using citrate concentration to determine postmortem interval of forensically-significant skeletal material


1Department of Anthropology, Ithaca College, 2Department of Chemistry, Ithaca College

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Many anthropological investigations have focused on developing methodology for the determination of postmortem interval (PMI) from forensically-significant skeletal material. Currently, no accurate method exists for this purpose. Using adult pig models, Schwarcz et al. (2010) presented results of a study designed to measure the postmortem loss of citrate content in bone. According to Schwarcz and colleagues, citrate content within living bone is fixed at a concentration of 2.0 ± 0.1 wt %, and then decreases at a constant rate after four weeks PMI. Based upon their findings, a PMI of up to approximately 100 years can be projected by measuring remaining citrate content within the bone. In an effort to replicate their findings, experiments using infant pigs were performed at the forensic decomposition site on Ithaca College’s Natural Lands in Ithaca, New York. Bone samples were taken from buried pigs at varying states of decomposition. The samples were chemically analyzed according to the methodology employed by Schwarcz and colleagues. Our results indicate an inability to establish a baseline citrate concentration in the bones across pig models as the initial wt % varied and did not decrease at a constant rate over time. Such differences in initial citrate concentration could greatly skew projected PMI results. Our analysis did not support citrate concentration in bone as an accurate measure of PMI. The differing composition of infant versus adult pig bones may partially account for these results and is discussed in detail.

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