Livor mortis.

Livor mortis, also known as hypostasis, is the discoloration of the skin due to the pooling of blood in the dependent parts of the body following death. The blood pools because the heart can no longer circulate the blood. Gravity will make the blood settle and the areas where it settles turns to a dark blue or purple color, which is termed 'lividity'.

The blood begins to pool immediately following death and is visible within a couple of hours. After the first two hours, the skin is bluish and blotchy. After five or six hours, the blotches become confluent and the skin will turn white when applied with pressure. After ten to twelve hours, the livid color remains even when pressed.

It is important to note that the blood will migrate to the lowest point in the body that it can travel. This may not necessarily be the lowest part of the body. For instance, if the victim was a hanging victim, the lividity will show in the feet, fingertips and earlobes. If the body is found in a supine position, the lividity will be found in the parts of the body touching the ground. Being able to identify the discoloration can be very useful in determining if a body has been moved after death.

Lividity is the result of the blood pooling within vessels. When the blood escapes the vessels, bruising is the result. Pathologists are able to notice the subtle appearance differences between lividity and bruises.

Certain poisons can also make the discoloration appear a different color. Carbon monoxide, for instance, will turn the skin a cherry pink color.