Forensic significance of decay-related spectral changes in ante-mortem and post-mortem injuries using ATR-FTIR spectroscopy

Abstract

Every year, more than 5 million deaths are attributed to injuries worldwide. However, accurately identifying and distinguishing the types of injuries in decomposed corpses is a significant challenge in forensic identification. Determining the cause of death in cases involving decomposed cadavers is particularly difficult, because traditional methods often lack conclusive evidence. To address this gap, this study aimed to explore the potential of attenuated total reflection/Fourier-transform infrared (ATR-FTIR) spectroscopy in analyzing the molecular composition changes in tissue samples from putrefied corpses. To simulate different environmental conditions, 54 experimental mice were randomly divided into three groups: ante-mortem injury (AI), post-mortem injury (PI), and non-injury (NI) groups, and their bodies were monitored at different time points. Subsequently, we conducted comprehensive analyses of these tissue samples using ATR-FTIR. The results indicate that under winter conditions, PC1 explained 78.3 % of the variance, whereas PC2 explained 15.4 %. Similarly, under summer conditions, PC1 explained 75.3 % of the variance, whereas PC2 explained 16.1 %. The results under both conditions, the AUC values of the ROC curve exceeded 0.9, indicating the reliability and accuracy of this method in discriminating ante-mortem injuries from post-mortem injuries on decomposed bodies, highlighting its significance in forensic investigations. This demonstrates the capability of ATR-FTIR technology to identify distinct molecular changes linked to ante-mortem and post-mortem injuries in decomposed corpses. The findings of this study underscores the forensic significance of understanding the molecular composition changes in decomposed cadavers. Therefore, ATR-FTIR is a valuable tool for differentiating ante-mortem and post-mortem injuries while also considering environmental factors.