What is livor mortis?

Livor mortis refers to the settling of blood in the body after death, which results in a purplish-red discoloration of the skin in the areas closest to the ground due to gravity. After the heart stops beating, blood no longer circulates, and gravity causes it to pool in the dependent areas of the body, typically starting within 20 minutes to a few hours after death. This process can provide valuable information in forensic investigations, including the time of death, as well as indicating the position of the body at the moment of death.

The other options describe different post-mortem phenomena. Stiffening of muscles refers to rigor mortis, which follows livor mortis and involves the rigidity of muscle tissues. Cooling of the body is known as algor mortis and involves the loss of body heat after death. Decomposition of tissues happens much later in the post-mortem process and involves the breakdown of body tissues. Each of these processes is important in forensics but specifically, livor mortis is the phenomenon of blood settling due to the cessation of circulation.