Rigor Mortis,
Rigor Mortis is one of the recognizable signs of death that is caused by a chemical change in the muscles after death, causing the limbs of the corpse to become stiff. The body’s muscles may contract in seemingly random and bizarre ways even though the body is dead. After a muscle contracts, ATP expenditure is required to release the myosin head of a thick filament from its binding site on the thin filament. Since all metabolic processes have come to a halt in a dead body, no ATP is produced, they become “stiff and locked” into place.
Livor Mortis
Livor mortis or postmortem lividity or hypostasis is the setting of blood in the lower portion of the body, causing a purplish red discoloration of the skin, when the heart is no longer agitating the blood, heavy red blood cells sink through the serum by action of gravity. This discoloration does not occur in the areas of the body that are in contact with the ground or another object, as the capillaries are compressed. Coroners can use the presence or absence of livor mortis as a means of determining an approximate time of death. It can also be used by forensic investigators to determine whether or not a body has been moved (for instance, if the body is found lying face down but the pooling is present on its back, investigators can determine that the body was originally positioned face up). Livor mortis starts 20 minutes to 3 hours after death and is congealed in the capillaries in 4 to 5 hours. Maximum lividity occurs within 6-12 hours.
Algor Mortis
Algor mortis is the reduction in body temperature following death. This is generally a steady decline until matching ambient temperature, although external factors can have a significant influence. As decomposition occurs the internal body temperature tends to rise again.
