Accurate estimation of the post-mortem interval (PMI) remains a significant challenge in forensic investigations, particularly when conventional methods, such as body temperature, rigor mortis, and entomological analysis, are confounded by environmental variables or late-stage decomposition. The epigenetic clock concept, which assesses DNA methylation patterns at specific cytosine–phosphate–guanine (CpG) sites, has recently emerged as a promising molecular tool for PMI estimation. Originally developed to measure biological age in living individuals, models such as Horvath’s, GrimAge, and PhenoAge have shown potential in forensic contexts due to their tissue specificity and relative post-mortem stability across biological matrices, including blood, muscle, bone, and dental pulp. However, to date, the epigenetic clock concept has not been validated for PMI estimation, limiting direct forensic application. These methylation-based tools can be tested for more objective and reproducible PMI estimates, especially during early to intermediate post-mortem intervals, and can be further enhanced by integrating with protein degradation or microbiome-based analyses. However, the forensic application of the epigenetic clock concept faces multiple challenges. Post-mortem DNA degradation, particularly in tropical climates, compromises methylation signal integrity and limits the reliability of time-sensitive analyses. Most existing models are trained on living datasets and lack post-mortem calibration across diverse populations and decomposition conditions. Additional barriers include the high cost of sequencing technologies, infrastructural limitations in low-resource settings, and the absence of universally accepted forensic validation protocols. Ethical concerns regarding genetic data privacy and the legal admissibility of molecular evidence must also be addressed. Future studies should prioritise the development of forensic-specific adaptations of the epigenetic clock concept tailored to regional and environmental contexts, establish standardised protocols for PMI estimation, and promote interdisciplinary collaboration among forensic pathologists, molecular biologists, and legal authorities. With rigorous validation and ethical oversight, the epigenetic clock concept may significantly enhance the accuracy and objectivity of medico-legal death investigations.
Alwis et al. (Mon,) studied this question.