Estimation of Post-mortem Interval Based on Livor Mortis using a Colorimeter in Thai Populations

OBJECTIVE Livor mortis is a helpful and widely used method of estimating postmortem interval (PMI) in Thailand. This study aimed to investigate the value of a colorimeter as a tool for estimating the PMI. METHODS The color of livor mortis and control skin in 80 cadavers whose PMI was within 12 hours was measured by a colorimeter. The L* (brightness), a*b* (chroma and hue), and ∆E* values were compared to the control skin values. Statistical analysis was performed to determine the relationship between PMI and skin color before and after application of a specific pressure. RESULTS The results showed that colorimetric parameters were only weakly correlated with the PMI. An univariable analysis of ∆E* values was performed and showed good discriminatory power, with an area under the ROC curve of 0.82. The recommended cut-off value of ∆E* was 14 for the discrimination between early PMI (less than 6 hours) and late PMI (6-12 hours), in which the sensitivity and specificity were 72.5% and 80%. CONCLUSIONS The findings in this study reinforce the utility of colorimetric measurements in PMI estimation. With additional study and a larger sample size, the estimation of PMI could be established for general use in forensic practice.