Time of Death Presentation Summaries
Algor Mortis is described as a rate method in which the change produced by a process which takes place at a known rate which was either stopped or initiated by death. Algor Mortis is the most resourceful method of measuring the time of death during the first twenty four hours that someone is dead. However, many factors can make an input in the estimating time of death. Algor Mortis is the process of inserting a thermometer into either the rectum or the stomach. A chemical thermometer must be 10-12 inches long and have a range of 0-50 degrees Celsius. The thermometer must be read in the body and as early as possible to prevent factors from changing the temperature. Factors that can affect the bodies original temperature and after death temperature: environmental temperatures (which must be recorded at time body was first discovered and any changes that happen,) if the body is lying on a cold surface or not, fall in body temperature largely results upon the radiation, evaporation, and convection, if the body is wet or not, original body temperature, if disease is present in the body, the size of the body, clothing and coverings, movement and humidity in the air. The rate at which a body cools can be described in a sigmoid curve (“S”-curve), when temperature is plotted against time. In addition, there is also a temperature plateau in which the body maintains a temperature for a while. This method can not be used in every case, it must be used only when conditions are easy to assess.
Rigor Mortis is the point at which the body stiffens after death. Death is followed by immediate muscle relaxation. The stiffening of muscles which follows is known as Rigor Mortis. The muscles then relax for a second time after Rigor Mortis. The first investigation into Rigor Mortis was by a man named Nysten, in 1811. During Rigor Mortis, the joints become fixed and can only be moved slightly if the body is at certain angles. Rigor Mortis involves the voluntary and involuntary muscles. Rigor Mortis results from a chemical change in the muscle protein. After death, the muscle tissue and all other oxygen dependent processes rely on ATP, which in turn relies on anaerobic glycolysis. When this glycolysis is depleted, the body locks up, and the body is now in the state known as Rigor Mortis.
Livor Mortis is when the blood settles in the lower parts of the body, due to the lack of circulation by an alive pumping heart and due to gravity. It is bluish purplish in color. The parts of the body that are pressed against something, (even the most mild pressure applied) will not show signs of Livor Mortis due to the compressing of the capillaries. Livor Mortis begins about 20 minutes to 3 hours after death and congeals within 4 to 5 hours, because the blood becomes permanently incoagulable due to a release of fibrinolysins (an enzyme). The maximum of the lividity will occur between 6 to 12 hours after death. The body becomes “fixed” after about 10-12 hours (meaning that the body will not immediately change the coloration). If the body is moved after death, Forensic scientists can identity this through the Dual Lividity, which is when there are two “poolings” of the blood. This is quite a reliable technique because it gives forensic investigators a basic idea of the position and method of death. Things that can be discovered: If the body was hung for example there is primary pooling in the legs, if the body was found face up but lividity is on the back then we can tell that the body was moved from somewhere between 8-12 hours (however this is inexact determination). If the person was poisoned or died from Carbon Monoxide or the body was refrigerated or clothes in wet clothing then the colors will vary from shades of pink to red to purple. However sometimes it can be unreliable due to the fact that it is not always detectable in certain individuals. It helps forensic scientists (if examined quickly) determine if the person in question died recently or not by a simple test of “thumb pressure” (Applying pressure with the thumb to make the skin “blanche” or turn white, which can indicate that the body’s blood is still pooling and therefore died recently.
Putrefaction is the decomposition of tissues into gases, liquids, and salts. The rates of decomposition vary depending on air temperature, humidity, and age. When temperatures are between 70-100 degrees, the conditions are best for rapid putrefaction. When the temperature is above or below that range, it is slowed. The skin and many internal organs become discolored, and the formation of gases in the abdomen causes the body to swell. Casper’s Dictum tells us that one week of putrefaction in air is equal to two weeks in water, which is equal to eight weeks in soil, given the same environmental temperature. By studying the decomposition, investigators can approximate a time of death, just based on surrounding conditions, age, weight, etc. The bodies of children are reduced to complete bone in about five years, while adults take about ten years.
Our group’s two topics discussed Mummification and Vitreous Humour Potassium. To some up both of the topics this briefly overviews Mummification and Vitreous Humour Potassium. Mummification is basically dehydration of tissues. The body shrivels up much like a grape would become a raison and converts into a leather/parchment like texture. The skin remains in-tact in this texture around the bones. During the mummification process they remove the internal organs and where they either decompose or are preserved. Mummification occurs in a dry heat are, like that of a desert. This climate dehydrates the skin creating the leather like texture. Vitreous Humour Potassium is used to identify the time of death. They use potassium to find pretty close to the accurate time of death. They can predict within 95% the time in up to 100 hours of post mortem. They sample the potassium levels through the eyes which can show the ante-mortem time. High urea values in the vitreous humour reflect the ante-mortem retention levels. Using these potassium concentrated values they can predict the ante-mortem values of up to 120 hours.
Adipocere (Grave Wax)- is a waxy substance that appears as early as a month after death, usually 5-6 months and sometimes up to 3 years, depending on environmental conditions (warm, moist, anaerobic environments favor adipocere formation), first appearing on fatty body parts, such as the cheeks. It develops as a reaction between the fats, water, and hydrogen. Once it is formed it remains unchanged for years, slowing the decomposition and helping to preserve the body. It can preserve evidence of wounds and cloth imprints on the body. The presence of adipocere can show that the death occurred at least 3 weeks in the past, but its primary importance is in preserving marks, features, and injuries that can aid in identification and determine types and locations of injuries.
Digestive Tract Contents- Where food is in the digestive track can determine the time of death after the last consumption of food. Food passes through the esophagus within seconds and enters the stomach. If food is mostly undigested in the stomach, death probably occurred 1-2 hours after consumption. Within 4-6 hours, the stomach empties and food enters the small intestine. The small intestine empties within 12 hours of consumption. The rate of digestion can be altered by medication, sickness, liquid intake, and even fear, so the times are by no means precise. Some criminals try to make it look like death occurred more recently after the meal by feeding processed food to the corpse. This food will be less digested than normal because the stomach muscles stop after death, although the acids will have some effect. Digestive track contents are largely subjective, but can be helpful in determining a range of time in which death occurred.