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Determining Time of Death

Determining Time of Death. Module 2.1 Criminal Investigation Elgin Law Enforcement I. 3/17/2010. Introduction. Use of time of death in a homicide investigation

colin-patton
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Determining Time of Death

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  1. Determining Time of Death Module 2.1 Criminal Investigation Elgin Law Enforcement I 3/17/2010

  2. Introduction Use of time of death in a homicide investigation By the end of this presentation students will be able to recite different methods and techniques in determining a time of death in a homicide investigation Previous knowledge from TV/Movies/Video Games…..FORGET all of it. 3/17/2010

  3. Overview T.O.D. is used in coordinating the facts of an investigation (refute alibis, place victim in a place at time) Environment, Body Chemistry, and Time all play roles. Decomp. Time Lividity Temp. Text Rigor 3/17/2010

  4. Vocabulary Algor Mortis – Body Cooling Rigor Mortis – Muscular Stiffening After Death Livor Mortis – Pooling of blood due to gravity Postmortem Decomposition (Putrefaction) Adipocere – Skin Discoloration (Yellow) Mummification – Putrefaction by Dehydration Maceration – Fetus Decomposition. 3/17/2010

  5. Algor Mortis – (Body Cooling) Measuring Body Temp. Intra Abdominal Done with either rectally or abdominal spiked into liver GENERALLY – Spiking is more accurate An estimate is all that is available when using Algor Mortis to determine T.O.D. 3/17/2010

  6. Algor Mortis – Variables Victims “normal” internal body temp at T.O.D. (Fever, Illness) Acute ailments – Hypothermia, Heat Stroke Environmental Conditions – Humidity, Heat, Cold, Wet or Dry clothing on body, any clothing present, if so how much? Movement of air over the body, and ESPECIALLY immersion in water (water is a better conductor of heat). The size of the body – The greater the surface area of a body compared to its mass, the more rapid the cooling. The more obese, the slower the rate. 3/17/2010

  7. Rigor Mortis Results from a physio-chemical change in muscle proteins after a variable time post mortem Muscles will then stiffen or a period of time before coming back to a relaxed state. The faster the onset of R.M., the shorter its duration The best estimation is as follows: No RM and warm temp.-death within previous 3 hours, onset of RM – death within previous 3 to 9 hours, and full RM – more than 9 hours. RM will generally relax after 24 to 48 hours 3/17/2010

  8. Rigor Mortis - Variables Can be confused with Cadaveric Spasm Involuntary tightening of hands and arms at the last moment of death due to the psycho traumatic nature of the death Cannot be reproduced after death by placing a weapon in a hand I.E. Drowning victim FIRMLY grasping weeds from bottom of a lake proves life at the time of entry into the lake Can be confused with Heat Stiffening Skin shrinkage due to burns will stiffen arms and legs Can be confused with Freezing of body RM will not progress until after significant thawing of body has occurred 3/17/2010

  9. Livor Mortis – (Hypostasis, Lividity) Dark purple or reddish discoloration of skin due to the gravitational pooling of blood post mortem 30 to 60 minutes post mortem blood inside a body becomes incoagulable Lividity in parts of the body covered by clothes appears pink and the rest purple Lividity attains maximum intensity 12 hours post mortem 12 hours post mortem, Lividity becomes fixed and will redistribute 3/17/2010

  10. Livor Mortis – Continued Used in determining if body was moved post mortem Used to corroborate positioning of corpse post mortem Can be mistaken for hematoma Lividity attains maximum intensity 12 hours post mortem 12 hours post mortem, Lividity becomes fixed and will redistribute 3/17/2010

  11. Postmortem Decomposition (Putrefaction) Destruction of soft tissue by action of bacteria and enzymes. Changes in tissue color, evolution of gases, and liquefaction The most common bacteria causing putrefaction is commonly found in the human body ante-mortem in the respiratory and digestive tracts Any ante-mortem infection will hasten the decomposition rate, as will open portals for foreign bacteria to enter post mortem. 3/17/2010

  12. Postmortem Decomposition (Putrefaction) Obese decedents will putrefy faster than lean Victims who retained fluids decompose faster than those that were dehydrated at T.O.D. Warm temperatures and high humidity make for the fastest rate of decay, temps exceeding 105 degrees may retard or altogether halt the process as well as sub-freezing or near freezing temperatures. 3/17/2010

  13. Postmortem Decomposition (Putrefaction) First stages indicate a greenish discoloration of the skin along the lower back due to the largest concentration of bacteria filled fluids in the bowels. Followed by the groin and buttocks, to eventually work up through the chest and face area During this process the superficial veins and capillaries become visible through the skin to form “marbling”, changing the appearance of the skin to a dusky reddish green to purple/black 3/17/2010

  14. Postmortem Decomposition (Putrefaction) Destruction of soft tissue by action of bacteria and enzymes. Changes in tissue color, evolution of gases, and liquefaction The most common bacteria causing putrefaction is commonly found in the human body ante-mortem in the respiratory and digestive tracts Any ante-mortem infection will hasten the decomposition rate, as will open portals for foreign bacteria to enter post mortem. 3/17/2010

  15. Postmortem Decomposition (Putrefaction) Blistering of the skin becomes apparent and skin slippage is common Due to building gases in the abdomen it becomes distended and forced fluids out of other orifices of the body (nose, eyes, ears, mouth, vagina, rectum) Gases also build within loose tissue causing obvious swelling (scrotum, penis, labia majora, breasts, and face) Eventually, built up gases find an escape and the swollen tissue masses collapse On AVERAGE 36 to 72 hours post mortem begins the putrefaction process (Temperate below 80 degrees F) 3/17/2010

  16. Adipocere (Saponification) Modification of putrefaction Fatty tissues transform to an opaque yellow greasy wax-like consistency Warm, moist, ANAEROBIC environment will cause Adipocere to form faster than classic putrefaction….WHY? Important not to determine T.O.D. but to preserve identifiable traits in corpse. Under ideal conditions, Adipocere is not visible until 3 to 4 weeks post mortem 3/17/2010

  17. Maceration (Aseptic Autolysis) Non bacterial breakdown of a fetus that has died in utero (within the amniotic sack)…when would this be important in an investigation? Fetus needs to be dead for several days for maceration to occur and classical putrefaction will occur immediately upon delivery of stillborn Body will have rancid odor, but NO gas formation has occurred 3/17/2010

  18. Mummification Another modification of putrefaction in a dehydrated state Common in Arizona desert deaths or body discardations (NOTE – temp plays no role, simply lack of humidity) The body shrivels and skin turns a brown leathery consistency Can occur in man made conditions such as consistent dry air flow over the body (Heating ducts, chimneys) Valuable as an Id. Tool, not as a T.O.D. claculator Ideal conditions can cause mummification within 2 to 3 weeks 3/17/2010

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