Unit 7: The Body 7.2 The Body after Death

Rigor Mortis Stiffening of skeletal muscles following death. Starts within 2 hours after death. Affected by factors like ambient temperature, body weight, clothing, illness, physical activity prior to death, & sun exposure. Rigor progresses starting from the eyes and progressing predictably to the head, neck, torso, and limbs. Rigor releases following the same progression.

Livor Mortis Livor mortis is the settling of blood, resulting in a reddish or purplish color pattern. Lividity can indicate the position of the body after death. Lividity usually begins between 30 minutes and 2 hours. It becomes fixed between 8 and 12 hours after death. When lividity becomes fixed, then the distribution of the pattern will not change even if the body’s position is altered or if the skin is pressed.

Algor Mortis Algor mortis is the cooling rate of the body after death. At a crime scene, the body temperature is obtained through: Rectal temperature Liver temperature Glaister equation: 98.4°F - internal temperature/1.5 = hours elapsed since death Generally the body cools 1 to 12 degrees Fahrenheit per hour until it reaches the surrounding temperature.

Effects that Influence Algor Mortis Temperature of the surrounding environment Type of clothing on the body Wetness of the clothing Air movement Layers of clothing Size of the individual

Post Mortem Interval Calculating the PMI becomes more precise as more factors are considered. Temperature Stiffness Approximate Time of body of body Since Death Warm Cold Not stiff Stiff Not dead more than 3 hrs Dead between 3 and 8 hrs Dead 8 to 30 hours Dead more than 30 hours

Stomach Contents If undigested stomach contents are present then death occurred zero to two hours after last meal. If the stomach is empty but food is in the intestines, death occurred at least four to six hours after a meal. If small intestines are empty but waste is in the large intestines, then death probably occurred 12 or more hours after a meal.