8. Dead Still
Rigor mortis, the stiffening of the body after death, is caused by a loss of Adenosine Triphosphate, a process that forces the body’s muscles to contract and become stiff. Rigor mortis affects small muscles before larger ones and begins around two hours after death. After all the muscles have contracted, rigor mortis lasts between 36 and 48 hours, after which the body reverses the process and returns to a limp state. Rigor can be reversed early by stretching the muscles.
A body in warm temperatures will stiffen more quickly than a body in a colder environment. This is why drowning victims are often still flaccid when pulled out of the water even if they have been submerged for several days. Rigor is also sped up if there has been intense physical activity close to the time of death.
Forensics use rigor mortis to help them determine the time of death: If a body is rigid, the victim has likely died within 48 hours. This method is not always accurate, however, due to the many factors that can affect the timeline of rigor.