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Death: Meaning, Manner, Mechanism, Cause, Time

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Presentation on theme: "Death: Meaning, Manner, Mechanism, Cause, Time"— Presentation transcript:

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


3 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”

4 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

5 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

6 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

7 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?

8 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)

9 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

10 Time of Death (TOD) many factors are used to estimate TOD

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

12 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)

13 Rigor Mortis literally means DEATH STIFFNESS temporary

14 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

15 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

16 Rigor Mortis

17 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)

18 Rigor Mortis

19 Algor Mortis literally means DEATH HEAT temperature loss generally,
- lose 1.4oF per hour for the first 12 hrs - lose 0.7oF per hour after 12 hrs until body reaches temp of surroundings

20 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

21 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

22 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

23 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.

24 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

25 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

26 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

27 Blow fly maggot

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

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

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

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

32 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

33 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.

34 Bugs seen at end stage

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