Anaya Garg

Accurate post-mortem interval (PMI) estimation remains a central challenge in forensic science, particularly once soft tissues are lost and conventional indicators such as algor mortis, rigor mortis, and insect activity lose predictive value. Bone-resident microbial communities offer a biologically grounded alternative. Prior work demonstrates that enteric bacteria migrate into skeletal structures via neurovascular canals early in decomposition, forming biofilms that are preserved long after soft tissue breakdown. These communities show predictable, time-linked succession patterns, suggesting that bone may serve as a stable substrate for PMI estimation. This project evaluates whether microbial communities within post-mortem bone can serve as reliable PMI biomarkers and compares these patterns across controlled and burial environments. Using 8 rat carcasses sampled over the period of a week, femoral bone was extracted, pulverized, and subjected to DNA isolation using a modified protocol derived from the DNeasy PowerSoil Pro Kit. Through iterative optimization, including decalcification adjustments, modified lysis steps, and increased bead-beating intensity, we established a consistent, replicable protocol capable of recovering microbial DNA from the interior of post-mortem bone. Preliminary sequencing confirms the presence of endogenous and translocated microbial DNA within the bone matrix, validating the biological premise of bone-based PMI estimation. Ongoing 16S rRNA analyses will identify high-abundance genera, characterize time-dependent community shifts, and evaluate environmental influences on succession. Establishing both the feasibility of microbial DNA recovery and the presence of structured bacterial communities provides a critical foundation for developing a standardized, bone-derived “bacterial clock” that extends PMI estimation well beyond the limits of current methods.