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.