Assessing the Impact of Lactic Acidosis at the Time of Death on the Rate of Development of Rigor Mortis
Mentor:Renee Garcia, Professor of Anthropology, Saddleback College
Forensic anthropologists oftentimes are called upon to make a determination of the post-mortem interval, or PMI to support their findings to either include or exclude a suspect from suspicion. The PMI is the length of time that elapses between time of death and discovery of the body. The determination of the post mortem interval is, in most cases an approximation. The onset and course of such conditions as rigor mortis are important factors in assisting in PMI determination. In the current study, it was hypothesized that the presence of lactic acidosis just prior to death accelerates the time frame of the development of rigor mortis from its commonly accepted time frame. As a result the possibility that the victim was acidotic at the time of death should be considered when calculating the onset of rigor mortis to ensure the most accurate determination of PMI. Findings indicated that lactic acidosis can arise from a variety of conditions found just prior to death – including carbon monoxide poisoning; asphyxiation; opioid overdose; and fleeing from an attacker. Discussion is presented that lactic acidosis may provide the intracellular chemistry to stimulate the early onset of the muscle stiffening seen in rigor mortis. Because of the variation in time of onset of rigor mortis if lactic acidosis is present just prior to death, further study may be required to develop modifications to the accepted rigor mortis time frame used by forensic anthropologists.