What is rigor mortis?

Rigor mortis refers to the postmortem muscle stiffening that occurs after death. This physiological process is caused by biochemical changes in the muscles, specifically the depletion of adenosine triphosphate (ATP), which is necessary for muscle contraction and relaxation. After death, the body’s temperature begins to drop, and the muscles start to stiffen due to the accumulation of calcium ions within muscle cells. This stiffening typically begins within a few hours after death and can last for several days before the body eventually relaxes again as decomposition progresses. Rigor mortis is a key indicator that forensic scientists and medical examiners use to help estimate the time of death and assess the postmortem interval.