death: meaning, manner, mechanism, cause, time chapter 11
TRANSCRIPT
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”
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
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
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
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?
Cause of Death (COD)the reason someone dies is the CODdisease, 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)
Mechanism of Deaththe specific body change that brought
about cessation of lifeex: 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
Livor Mortis
literally means DEATH COLORRBC break down & spill contentshemoglobin turns
purple when it spillspurplish color visible
wherever blood pools (lividity)
Livor Mortis
2 hrs after death: lividity begins8 hrs after death: discoloration permanentbetween 2 and 8 hrs after death: if you press
skin, discoloration disappearsambient 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)
Rigor Mortisno visible rigor:
<2 hrs or >48 hrsvery rigid (full rigor):
~12 hrsrigor only in face & neck:
just over 2 hrssome rigor in body, none in face:
more than 15 hrs ago
Rigor Mortisstiffness 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
Rigor Mortisfactors 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)
Algor Mortisliterally means DEATH HEATtemperature lossgenerally,
- lose 1.4oF per hourfor the first 12 hrs- lose 0.7oF per hourafter 12 hrs untilbody reaches tempof surroundings
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
Stages of Decompositionwithin 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
Forensic EntomologyFlies arrive within 10 minutes of deathType 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
Four development stages of flies:egg Hatch into a larva or maggotcrawls 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.
adult fly emerges from pupaAdults mate, and the females will
lay more eggs onto corpses. Lays eggs in natural body openings Eggs/ worms in head area firstThen reproductive/ excretory regionsTrunk at very late stage
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 cycleDrugs – poisons (arsenic) will slow
down
Order of fliesBlow flies and flesh flies – arrives in 10
minutesBlow flies will lay eggs on corpse on
day 1Will see maggots by day 2
House flies come after the flesh fly and blow fly
Will lay eggs by day 2 and maggots will be seen by day 4
The next fly to follow ONLY IN URBAN areas is the skipper fly
Will lay eggs by day 5; maggot by day 7
Fresh stage0-3 days Protein, carbs break down- Blows flies and flesh flies- no smell yetBloated stage- 3-7 days Decay starts- smell starts-
abdomen bloats due to CO2 made by bacterial respiration
House flies and predatory flies
Decay stage (putrid smell due to gas release)
8-18 days – total decay- all body bloats; abdomen breaks down – fluid seepage
Ants, cockroaches, beetlesOver 18 days – drying out phase; flesh
falls off; worms not presentMainly bugs that can feed from bones
such as beetles.