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

Death: Meaning, Manner, Mechanism,

Cause, TimeChapter 11

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

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

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 Mortisliterally means DEATH STIFFNESStemporary

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 Mortis

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)

Rigor Mortis

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

Blow fly maggot

Flesh flies will deposit maggots on corpse on day 1

Day 1-3 protein and carbs

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

Predatory flies appear next to feed on the flies , NOT ON THE CORPSE

These are beetles, wasps etc

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.

Bugs seen at end stage