Estimation of the postmortem interval by chemical means

Area of Science:

• Forensic Science
• Biochemistry
• Toxicology

Background:

• Accurate estimation of the postmortem interval (PMI) is crucial in forensic investigations.
• Chemical analysis of cadaver fluids offers potential methods for determining PMI.
• Existing methods have limitations in reliability and environmental independence.

Purpose of the Study:

• To review the literature on chemical analysis of cadaver fluids for postmortem interval estimation.
• To identify the most reliable chemical markers for PMI determination.
• To assess the utility of various chemical analyses in different postmortem timeframes.

Main Methods:

• Literature review of studies on chemical analysis of blood, cerebrospinal fluid (CSF), and vitreous humor.
• Analysis of specific chemical components including amino nitrogen, nonprotein nitrogen, ammonia, creatine, inorganic phosphate, potassium, and magnesium.
• Evaluation of the correlation between chemical concentrations and time since death.

Main Results:

• Amino nitrogen, nonprotein nitrogen, ammonia, creatine, and inorganic phosphate in blood and CSF are useful for early PMI.
• Potassium content in vitreous humor demonstrates a linear increase between 12-100 hours postmortem.
• Vitreous potassium rise is largely unaffected by environmental factors, making it a robust indicator.

Conclusions:

• No single chemical measurement provides a completely reliable PMI estimate.
• Combinations of chemical analyses can serve as valuable adjuncts in determining PMI.
• Vitreous humor potassium analysis is a highly accurate method for estimating PMI within a specific timeframe.