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Time Since Death TODTime of Death

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Forensic science provides a number of solutions to solving the mystery question of when a person died. Generally, the longer it has been since the death, the less accurate the estimation given by forensic pathologists.

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Cause of death - disease or injury that initiates the lethal train of events leading to death. Postmortem - after death

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Postmortem Interval PMI. The time since death

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Manner of Death - death occurs in one of four manners: A) natural, if caused solely by disease; B) accidental, if it occurs without apparent intent; C) suicide, if caused by the deceased; D) homicide, if someone other than the deceased caused it.

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Coroner - an elected official with death investigation duties. Medical Examiner - government official, always a physician and often a forensic pathologist, charged with investigating sudden and unexpected deaths or deaths from injuries.

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Autopsy The internal medical examination of a body used to determine the cause and circumstances of death.

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Body Temperature The pathologists/coroners record the temperature of the body, the temperature at the scene of crime, the weight of the victim and all other appropriate variables, which are then applied to a formula designed to predict the time since death.

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Visceral Temperature The Temperature of the internal organs, particularly those within the abdomen and thorax.

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Diagram showing how liver temperature, relative to room temperature, determines time of death. Since the temperature of a dead body falls at about one-and-a half degrees per hour, the 87 degree liver temperature indicates death at 6-7 hours before.

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The usual equation is: 37oC - 1.5 oC This formula equates to the body temperature (37oC), which loses 1.5oC (34.7 Fahrenheit) per hour until the temperature of the body is that of the environment around it; known as the ambient temperature.

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Hardening Stiffening of the corpse occurs between just 30 minutes and 3 hours after death. The process is called rigor mortis and occurs as the muscles in the body begin to stiffen from a lack of blood and oxygen

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Types of Mortis Algor mortis - the postmortem cooling of the body. Ante mortem preceding death Antigens - foreign substances in the body that are capable of causing disease. Rigor mortis - Stiffening of the body after death; a time dependent change that helps determine time of death.

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Primary Flaccidity The general relaxation of the entire muscular system after death. This will usually only last between two to eight hours. Secondary Flaccidity The secondary relaxation of the bodys muscles following death.

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Rigor mortis first becomes apparent in the eyelids and jaws of the victim and spreads throughout the whole body in approximately 6 to 12 hours, before receding again after another 6 to 12 hours.

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Truth Lies in the Eyes The eyes of a victim can also hold answers to the time of death, as a thin cloudy film is developed over the eye within 3 hours after death has occurred. The eyeballs become softer as a result of less fluid pressure behind the eye and the degree to which this has occurred can be used as a measure of the time since death.

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Skin Color The color of the corpse will also help determine the time of death from about 48 hours and onwards. From approximately 48 hours after death, bacteria begins to breed on the skin, giving the skin an evidently greenish tone. The tinge starts in the lower stomach area, spreading outwards and affecting the hands and feet last. Approximately 4-7 days after death, the skin will acquire a marble-like appearance, as the veins in the body become closer to the surface, thus becoming more easily visible.

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Blood Pooling The pooling of the blood can be a vital clue in determining the time of death and is known as hypostasis. This occurs when the blood ceases flowing, settling in the lowest parts of the body and in turn, causing the skin to become pink and red in color. This process is complete in up to 6 hours after death. The main use of blood pooling analysis actually lies in helping to determine the death manner (noting that the location of the blood pools indicates the upright position of the body at the time of blood pooling) The process does however, form a method of predicting the time since death.

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Livor Mortis Livor Mortis - discoloration of dependent parts of the body after death.

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Hypostsis - Lividity The pooling of blood at the lowest parts of the body. Usually commences between six and eight hours after death has occurred.

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Exsanguination - bleeding to death.

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Digestive System Chewed food will firstly pass through the esophagus and then down into the stomach within seconds of the initial swallowing. After 3 hours, the food then leaves the stomach and heads toward the small intestines. 6 hours after eating a meal, the food will have traveled half way through the small intestines and begin moving through the large intestine. Where the victim's small intestine is empty, it suggests that the victim ate his or her last meal approximately 8 hours before death. The digestive process usually takes a bit more than a day, but it can be affected by sickness, liquid intake, fear or drug intake.

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Forensic Entomology Flies and maggots also provide an approximate time of death, very useful for cases where the body has been long dead. Only certain insects will feed and lay eggs on a dead corpse and forensic entomologists study these insects, their larvae cycles and thereafter can determine whether a body has been dead for just one day or up to 3 or 4 weeks.

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The Body Farm http://www.youtube.com/watch?v=GSDCiOW 81mk 5 min http://www.youtube.com/watch?v=GSDCiOW 81mk

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Putrefaction One of the final changes to take place in the human body, essentially the anaerobic bacterial digestion of the remains. Adipocere A waxy, soap-like substance that forms on corpses during decomposition under specific conditions. Also known as grave wax.