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Death: Meaning, Manner, Mechanism, Cause, Time

Death: Meaning, Manner, Mechanism, Cause, Time. Chapter 11. Back in the day …. 17 th 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”?) “waiting mortuaries”. Death is ….

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Death: Meaning, Manner, Mechanism, Cause, Time

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  1. Death: Meaning, Manner, Mechanism, Cause, Time Chapter 11

  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”?) • “waiting mortuaries”

  3. Death is … • … cessation (end) of life? • … “irreversible cessation of blood circulation”? • … cessation of all brain activity? • hard to give a single definition of – it is a PROCESS rather than an instant event

  4. 1st stage of death: STOPPAGE • heart stops  cells begin to die (no O2)  body processes fail (no O2)  nerves, muscles, organs, brain fail • autolysis: cell breakdown

  5. 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

  6. 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?

  7. 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)

  8. 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

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

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

  11. 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)

  12. Rigor Mortis • literally means DEATH STIFFNESS • temporary

  13. 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

  14. 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

  15. Rigor Mortis

  16. 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)

  17. Rigor Mortis

  18. 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

  19. 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

  20. 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

  21. 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

  22. Four development stages of flies: • egg • Hatch into a larva or maggot • crawls like a caterpillar and actively consumes food to grow quickly. • Maggots will pass through several instars or stages – keep getting bigger and molt at end of every stage • Next stage: a dark immobile pupa.

  23. adult fly emerges from pupa • Adults mate, and the females will lay more eggs onto corpses. • Lays eggs in natural body openings • Eggs/ worms in head area first • Then reproductive/ excretory regions • Trunk at very late stage

  24. Insects are ectothermic-body needs to be warmed by outside to be able to grow • Will speed up process in hot climates/slow in cold regions • Drugs – cocaine will speed up life cycle • Drugs – poisons (arsenic) will slow down

  25. Order of flies • Blow flies and flesh flies – arrives in 10 minutes • Blow flies will lay eggs on corpse on day 1 • Will see maggots by day 2

  26. Blow fly maggot

  27. Flesh flies will deposit maggots on corpse on day 1 Day 1-3 protein and carbs

  28. House flies come after the flesh fly and blow fly • Will lay eggs by day 2 and maggots will be seen by day 4

  29. The next fly to follow ONLY IN URBAN areas is the skipper fly • Will lay eggs by day 5; maggot by day 7

  30. Predatory flies appear next to feed on the flies , NOT ON THE CORPSE • These are beetles, wasps etc

  31. Fresh stage • 0-3 days Protein, carbs break down • - Blows flies and flesh flies • - no smell yet • Bloated stage- • 3-7 days Decay starts- smell starts- abdomen bloats due to CO2 made by bacterial respiration • House flies and predatory flies

  32. Decay stage (putrid smell due to gas release) • 8-18 days – total decay- all body bloats; abdomen breaks down – fluid seepage • Ants, cockroaches, beetles • Over 18 days – drying out phase; flesh falls off; worms not present • Mainly bugs that can feed from bones such as beetles.

  33. Bugs seen at end stage

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