When the Dead Speak..... |
The autopsy is a very important source of information for the forensic scientist. After graduating from medical school, a forensic pathologist must do a two year internship and must pass the board exam with the American Board of Pathology. Individuals with this certification are able to: ...estimate the time of death ...establish the cause of death ...infer the type of weapon used ...distinguish a homicide from a suicide ...establish the identity of the desceased ...determine the additive effect of trauma or pre-existing conditions. Coroners and Medical Examiners are the titles given by various states to the official pathologist in charge of investigations related to cause of death outside a hospital.Coroners do not have to be medical doctors, but must have medical training and are not exempt from civil liability for acts of negligence. Medical examimers are exempt. |
Autopsies through the ages. |
Determining the Time of Death.... Rigor Mortis: Immediately upon death, muscles all relax and become flexible or flaccid. But as glycogen in the muscles is converted to lactic acid, the muscles become rigid this occurs due to metabolism in the muscle continuing anaerobically for a short period after death. All muscles, large and small become rigor at the same rate, but it will become more obvious in smaller muscles first. This process occurs more quickly when the body is exposed to warmer temperatures and proceeds more slowly when the body is cooled. An examiner will calssify the degree of rigor as mild, early, moderate or complete and the determination is purely subjective. Rigor mortis is affected by temperature, illness, activity before death, and the physical conditions of the environment where the body is found. The onset of rigor mortis is immediate manifesting itself between 1-6 hours, maximum being at 6-24 hours and disappears between 12-36 hours. Livor Mortis.... Livor mortis is teh way blood settles after death to the dependant parts of the body. Blood settles to the lowest points of the body once the heart has stopped pumping. The areas where blood has settled will become dark and take on a dark bluish or purple color. Visibility will depend on the level of pigmentation in the deceased skin. Because the heart stops beating at death, livor begins very soon afterward. This darkening maximizes at 8-12 hours after death and does not disappear. Tardeau's spots (petechial hemorrhages): These small spots are caused by broken capillaries and when they occur in the whites of the eye, are suggestive of asphyxia or suffocation. The spots maybe 4-5 mm in diameter. Algor Mortis..... The body cools uniformly after death. Once metabolism has ceased, the body immediately begins to cool down. Body temperature after death can be raised or maintained due to activity, illness, decompositon, infection and absorption of heat from the surroundings. In determining the rate of cooling, consideration must be given to the clothing, victim size, activity and physical factors. The one equation used to determine the cooling rate is known as the GLAISTER EQUATION: 98.4% minus measured rectal temperature _____________________________________ = appr. Hrs. 1.5 since death Ocular Changes: The cornea becomes cloudy within 2 hours or less if the deceased dies with the eyes open, closed it will be 12-24 hours. On the 3rd post mortem day, the corneas become opaque. When gases begin to collect in the body, the eyes may actually bulge out of the socket, but when advanced decomposition sets in, the eyes become endopthalmic, or retracted into the socket. Stomach Contents: When we begin eating, it is approximately 10 minutes before food begins to leave the stomach. A light meal will have left the stomach in 1-2 hours, a medium meal 3-4 hours, and a very heavy meal, 4-6 hours. One variable to be considered is the emotional state of the individual at the time of death since the stomach rate varies with emotional stress. Vitreous Potassium: Potassium concentrations ar higher inside the cell than they are in the plasma. After death the membrane the level of potassium inside and out moves to become equal. This equilibrium is reached at a steady rate change in the level of potassium inside the cells. The formular used for this determination is: (7.14xK+concentration) - 39.1= hours since death. ** There are certain times due to location of the deceased when this formula can not be applied. |
When only the skeletal remains are found the following factors are important: ..found above or underground ...climate ...moisture ...elevation ...terrain ...protection ...insect, animal,human intervention |
Tache noire.... when the mucous membranes dessicate, the conjunctiva of the eye turns black. Putrefication... Upon death, the skin and mucous membranes begin to discolor to a green. Due to bacteria, body compartments become distended and may rupture. The break down of amino acid residues with sulfhydryl gorups produce a bad stench. If the body is in a very hot dry climate, rather than putrefication, mummification may occur. If the body is in a moist environment like a cave, fatty tissues become waxy instead of undergoing putrefication |
