Death: Meaning, Manner, Mechanism, Cause, Time

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