Role of Chemistry in Determining Time Since Death

Accurate post‑mortem interval (PMI) estimation is fundamental to forensic science but traditional macroscopic indicators rapidly lose reliability. This review explains how chemical and molecular techniques are redefining PMI estimation. Early work focused on measuring electrolytes in vitreous humor (VH); the linear increase of potassium following cellular membrane breakdown remains a robust marker. Other metabolites such as creatinine, urea, glucose and hypoxanthine in VH, blood and synovial fluid extend the estimation window. Post‑mortem biochemical processes are also summarised, autolysis and putrefaction degrade macromolecules, produce volatile organic compounds and gases, and alter pH and redox potential, forming biochemical clocks. Biological matrices including VH, blood, cerebrospinal fluid, urine, muscle, liver and brain each provide different advantages and challenges. The review surveys tissues like muscle, liver and brain and describes how electrolyte leakage, metabolite accumulation and protein degradation offer complementary time markers. Key markers encompass electrolytes, metabolites, enzyme activities, protein degradation patterns, microRNAs and volatile organic compounds. Analytical tools such as gas/liquid chromatography, mass spectrometry, NMR spectroscopy and ion‑selective electrodes enable sensitive measurement. Emerging multi‑omics and spectroscopic techniques (ATR‑FTIR, Raman) integrated with machine‑learning models enhance resolution and show promise for multi‑organ metabolomics and proteomics. The review also notes limitations: environmental variability, inter‑individual differences, drugs and ethical constraints necessitate multidisciplinary approaches. Future research directions stress multi‑marker models, entomology integration, portable devices and population‑specific databases.