Livor mortis or postmortem lividity or hypostasis (Latin: livor—bluish color, mortis—of death), one of the signs of death, is a settling of the blood in the lower (dependent) 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. The presence of livor mortis is an indication of when it would be irrelevant to begin CPR, or when it is ineffective to continue it if it is in progress. 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 the deceased's 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. The blood pools into the interstitial tissues of the body.