Cardiac blood phenethylamine as a potential biomarker for post-mortem interval in forensic autopsy cases

In forensic autopsy, estimating post-mortem interval (PMI) requires a combined analysis of macroscopic findings with histopathological, biochemical, and toxicological data. However, accurate assessment of PMI remains challenging, particularly in cases with advanced decomposition. Phenethylamine (PEA), a putrefactive amine, has been identified in various post-mortem samples including blood, tissues, and body surfaces. This study aimed to evaluate the association between cardiac blood PEA concentrations collected during forensic autopsies and PMI in forensic autopsy cases. Cardiac blood samples from 361 forensic autopsy cases were collected over 6 years and analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry. PMI ranged from 0.5 to 150 days (median: 1.29), whereas PEA levels ranged from 0 to 115.2 µg/mL (median: 0 µg/mL). When all cases were included, a moderate association was observed between PEA concentration and PMI (R² = 0.47). By contrast, among the 100 cases with detectable PEA (≥0.001 µg/mL), a strong positive correlation was observed (r = 0.84, p < 0.001), with the regression model y = 0.43x - 1.92 (R² = 0.71). Logistic regression analysis revealed that PMI was significantly associated with PEA detectability (odds ratio per 1-day increase in PMI: 1.04, 95% confidence intervals: 1.03-1.05, p < 0.001). These findings suggest that cardiac blood PEA may serve as a supplementary objective indicator for PMI estimation, particularly in decomposed corpses, although further studies are required to confirm its broader applicability.