The effect of temperature on the mechanical aspects of rigor mortis in a liquid paraffin model

Abstract Rigor mortis is an important phenomenon to estimate the postmortem interval in forensic medicine. Rigor mortis is affected by temperature. We measured stiffness of rat muscles using a liquid paraffin model to monitor the mechanical aspects of rigor mortis at five temperatures (37, 25, 10, 5 and 0 °C). At 37, 25 and 10 °C, the progression of stiffness was slower in cooler conditions. At 5 and 0 °C, the muscle stiffness increased immediately after the muscles were soaked in cooled liquid paraffin and then muscles gradually became rigid without going through a relaxed state. This phenomenon suggests that it is important to be careful when estimating the postmortem interval in cold seasons.