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ANT 205 - November 4th, 2013.doc

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Carolan Wood

Time Since Death • time since death is important to identifying and testing alibis 3 methods of time since death // 1. Corporal which relates to decomposition 2. Environmental which relates to insects and leaf layers, roots and artifacts 3. Habitual activities of a missing person Early Decompositional Stages are all done by the FORENSIC PATHOLOGIST! // Autolysis – the destruction of tissues by enzymes Putrefaction – the reduction and liquefaction of tissue BY BACTERIA Remember that all decompositional stages are affected by the environment! The more humid it is this can speed up decomposition. Soil and more alkaline will preserve something. Light directly relates to insect activity. Exposure to wind, water and snow as well are other decompositional changes. Burial conditions such as where and how deep the burial is affects decomposition. The presence or lack of clothing speaks to accessibility. Trauma or preexisting disease are also another set of decompositional changes. 1. ALGOR MORTIS – body cooling • dead bodies will instantly cool to ambient temperature • temperature rate is incluence by other factors of decomposition like: burial conditions etc • Covering a body before disposal will slow the rate of cooling Body fat slows down how fast you lose your original temperature You can estimate the elapsed time since death BY comparing the temperature of a corpse to the ambient temperature of an area. There is a problem with this in that bodies do not cool at consisten rates. Using Body Temperature to Determine Time Since Death // • The average adult corpse loses 1.5 degree F per hour in temperature climates • The average adult corpse loses head at 0.75 degrees F per hour in tropica climates • Algor Mortis is only useful up until about 18 hours after death, depending on environmental conditions 2. LIVER MORTIS – discoloration • blood will drain to the lower parts of your body • this is useful for up to about 30 mins to 4 hours post mortem • this becomes peaked at 8 to 12 hours • through this you can determine TIME SINCE DEATH • the position of the body upon death and if the body has been moved can be determined through this. At the low points of twhere the blood is pooling, the skin will be purple. Where there are pressure points and the skin is white, this means that no blood was able to reach there. • This pattern is formed and retained when the individual dies • This is limited by the short amount of time that you have for the time of death indicator. Darker skin makes to find this much harder. 3. Rigor Mortis – stiffening • at death MUSCLES WILL relax • the lower jaw drops • eyelids will lose their tension • muscles are soft and joints are flexible • muscle glycogen is convered into lactic acid, the pH level of a person will drop • as muscles become acidic it will also coagulate • the stiffening of the limbs and body begins to occur Putrefaction will increase pH • coagulant will start to liquefy and the body becomes flaccid • Rigor usually begins in the eyelids and face 1-4 hours PostMortem and will peak at 6-12 hours post mortem • At 24-36 hours, rigor begins to leave the body Later Decompositional Stages // • blue to green discoloration will occur in the lower abdomen. Bacteria and enzymes migrate from the bowel to the body tissue • This will spread throughout the abdominal region at 36 hours • Purple to black discoloration of the skin happens and the hemoglobin starts to break down From 36 to 48 hours the bloating of the face to your neck starts to happen. While putrefication encompasses the entire body at about 60 to 72 hours. 4 to 7 days later and gas + fluid exits the body orfices and hair and nails loosen with the shedding of skin starting to occur. Eventually soft tissue will collapse Saponification – converts fat into adipocere. This can only happen within wet conditions. This will only occur where fat is
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