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 hour for the first 12 hrs
- lose 0.7oF per hour after 12 hrs until body reaches temp of 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