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Death: Meaning, Manner, Mechanism, Cause, Time

Explore the various aspects of death, including the meaning, manner, mechanism, cause, and time. Learn about different types of deaths, the stages of decomposition, and forensic entomology. Discover how to determine the cause and time of death through scientific analysis.

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Death: Meaning, Manner, Mechanism, Cause, Time

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  1. Death: Meaning, Manner, Mechanism, Cause, Time

  2. Back in the day … • 17th century: anyone in a coma or with a weak heartbeat was presumed dead & buried • fear of being buried alive = cowbell in coffin (“saved by the bell”?)

  3. Manner of Death (MOD) • natural death (most common) - interruption/failure of body functions from age or disease • accidental death - unplanned events (car accident, falling from a ladder) • suicidal death - person purposefully kills oneself • homicidal death - death of one person caused by another • undetermined

  4. What’s the MOD? • A man with a heart condition is attacked and dies from a heart attack during the assault. Is the MOD accidental or homicide? • An elderly woman dies after being kept from receiving proper health care by her son. Is the manner of death natural or homicide?

  5. Cause of Death (COD) • the reason someone dies is the COD • disease, physical injury, stroke, heart attack, bludgeoning, shooting, burning, drowning, strangulation, hanging, suffocation, etc. • “proximate cause of death” is an underlying cause (as opposed to the final cause)

  6. Mechanism of Death • the specific body change that brought about cessation of life • ex: if COD is shooting, mechanism may be blood loss (exsanguination) or loss of brain function • ex: if COD is a heart attack, mechanism may be heart stopping to beat or pulmonary arrest

  7. Time of Death (TOD) • many factors are used to estimate TOD

  8. Livor Mortis • literally means DEATH COLOR • RBC break down & spill contents • hemoglobin turns purple when it spills • purplish color visible wherever blood pools (lividity)

  9. Livor Mortis • 2 hrs after death: lividity begins • 8 hrs after death: discoloration permanent • between 2 and 8 hrs after death: if you press skin, discoloration disappears • ambient temp affects time for lividity to set in (hotter = faster) • can reveal approximate TOD and position of corpse and if they’ve been moved (dual lividity)

  10. Rigor Mortis • literally means DEATH STIFFNESS • temporary

  11. Rigor Mortis • no visible rigor: <2 hrs or >48 hrs • very rigid (full rigor): ~12 hrs • rigor only in face & neck: just over 2 hrs • some rigor in body, none in face: more than 15 hrs ago

  12. Rigor Mortis • stiffness occurs because skeletal muscles can’t relax (they are contracted) due to presence of extra calcium • muscles control bone movement so joints appear to be rigid too

  13. Rigor Mortis

  14. Rigor Mortis • factors that affect rigor mortis include: - ambient temp (warmer = faster due to faster chem reactions) - body weight (thinner = faster due to less stored O2) - type of clothing (clothed = faster) - illness (sick/fever = faster) - level of activity before death (aerobic exercise = faster) - sun exposure (sunlight = faster)

  15. Rigor Mortis

  16. Algor Mortis • literally means DEATH HEAT • temperature loss • generally, - lose 1.4oF per hourfor the first 12 hrs - lose 0.7oF per hourafter 12 hrs untilbody reaches tempof surroundings

  17. Stomach & Intestinal Contents • also used to help determine TOD • 4-6 hrs for stomach to empty contents into small intestine • another 12 hrs for food to leave small intestine • 24 hrs for all undigested food to be released

  18. Stages of Decomposition • within 2 days - cell autolysis - green/purplish staining - marbled skin - discolored face • after 4 days - skin blisters - abdomen swells with CO2 • within 6 to 10 days - corpse bloats with CO2 - chest/abdominal cavities burst and collapse - fluids leak from body openings - eyeballs/other tissues liquefy - skin sloughs off

  19. Forensic Entomology • Flies arrive within 10 minutes of death • Type of insects follows a succession as the body undergoes changes from- • The fresh stage, to the bloating stage to the dry or skeletal stage when the skin falls of leaving teeth and bone

  20. Four development stages of flies: • egg • Hatch into a larva or maggot • adult fly emerges from pupa • Adults mate, and the females will lay more eggs onto corpses. • Lays eggs in natural body openings

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