Postmortem period, early

Previous studies have shown that muscle lysosomal hydrolases are released early in the postmortem period due to a decrease in intracellular ATP concentrations. The decreased intracellular ATP level causes the rupture of the lysosomal membrane (14), releasing hydrolytic enzymes (proteases, lipases, and glycosidases) that further potentiate the weakening of membrane integrity and cellular function. Furthermore, as the acidosis increases (due to the anaerobic conditions associated with cellular death) the intramuscular pH to levels reach that which are optimal for the activity of several lysosomal thiol proteinases. 

The aim of this chapter was to review the techniques and methods currently available to forensic investigators that can potentially estimate postmortem interval or postburial interval. The estimation of time of death or deposition is one of the most important factors that forensic experts are regularly asked to determine. Although numerous methods are available in the early postmortem period (i.e., forensic pathology), once the remains become decomposed the determination of PMI becomes much more difficult to estimate. Furthermore, the methods used to estimate the PMI of exposed remains cannot always be applied to buried remains. As a result, substantial research has been conducted in recent years in an attempt to identify an accurate method for estimating PMI or PBI of remains discovered in burial environments. 

Moriya F, Hashimoto Y. Redistribution of methamphetamine in the early postmortem period. J Anal Toxicol 2000 24(2) 153-5. 

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