Transcript Time of Death

Time of Death
The Face of Death
"All I desire for my own burial is not to be
buried alive." - Lord Chesterfield, 1769

17th Century
– Coma or weak
heartbeat = DEAD and
BURIED
– Fear of being buried
alive bell in coffin
 “Saved by the bell”
"Have me decently buried, but do not let my body be
put into a vault in less than two days after I am dead." deathbed request of George Washington.

Waiting Mortuaries
– Established in 17th century
– Those thought to be dead…placed on cots
and observed until body began to rot
 Now…. they’re dead

Is a person with a heartbeat alive even if
there is no brain activity?
– What do you think?
Cessation (Death – End of Life)

Somatic death
– Death of the entire body
– Legal definition:
 Death of upper brain & brain stem

Cellular death
– Death confined to cells or tissues in the body
“Irreversible cessation of circulation of blood.”

Lend me a looking glass;
If that her breath will mist or stain the
stone,
Why then she lives.
Shakespeare, King Lear
Autolysis

When a cell dies, it breaks down
– Breakdown = autolysis
 Definition: the destruction of a cell through the
action of its own enzymes

Once enough cells begin autolysis, life
cannot be restarted
– Cell membrane dissolves – enzymes and other
cell contents spill – digest surrounding tissues
Manners of Death

Natural
– death results from natural disease processes

Accidental
– Caused by unplanned events

Suicidal
– Person purposefully kills oneself

Homicide
– Caused by another person

Undetermined
Categorize Manner of Death

A man with a heart condition is attacked and
dies from a heart attack during the assault
– Accident or homicide?

An elderly woman dies after being kept from
receiving proper health care by her son.
– Natural or homicide?

Both cases = homicide. Proving in court that
manner of death was a homicide may be difficult
Cause of Death

Cause of death = reason someone dies

“Proximate cause of death” – refers to an
underlying cause of death… rather than
FINAL cause of death
– Ex: If someone is exposed to large amounts
of radiation and then developed cancer
 Proximate cause of death?
– Radiation exposure!
Mechanism of Death

Mechanism of Death = the specific change in
the body that brought about the cessation of
life
– Ex: If cause of death is shooting, what would be
the mechanism of death?
 Loss of blood, cessation of brain function or
exsanguination (total blood loss)
– Ex: If cause of death is heart attack, what would
be the mechanism of death?
 Heart stopping to beat or pulmonary arrest
Estimate Time of Death

Evaluate the stage of decomposition that
the body was found in
Rigor Mortis: Rigidity of Death
In mammals
 Body stiffening of muscles in the position that
they are in when death occurs
 First eyelids, neck, jaw, then other muscles
(from head to toe)

Rigor Mortis

How?
– Aerobic respiration stops,
anaerobic respiration
begins
 Conversion of sugar to
pyruvic acid to lactic acid
 2 ATP anaerobic vs. 36 ATP
aerobic
– Lack of ATP forces
muscles to stay contracted
Rigor Mortis
Inside cell
Ca2+ naturally flow from
fluid surrounding muscle
cells to inside the cell
 To relax muscles, Ca2+ must
flow back across the cell
membrane

– Requires ATP energy, not
enough ATP after death
– Muscles stay contracted
Fluid surrounding
muscle cells
Rigor Mortis

Timeline
– Begins 3-4 hours after death
– Maximum stiffness 12 hours after death
– Stiffness decreases until 72 hours after death
Cadaveric Spasms
Occurs at the moment of death
 Most common when person has died
violently
 Involves a certain group of muscles

– hand, forearm
Livor Mortis
“Death Color”

Lividity
– Dark purple discoloration of the skin resulting
from the gravitational pooling of blood to the
lowest points of the body
 Dependent on body position
– In deaths from carbon monoxide poisoning, it
is classically described as "cherry red“
– Onsets immediately
Livor Mortis

Duality of
distribution
– After 10-12 hours
lividity becomes
“fixed”
– If body is moved
there will be a dual
lividity pattern
Livor mortis
• What assumptions can be
made about the victim
based on lividity?
• If this victim was found
upright in a chair, what
else can be assumed?
• In average environmental conditions/temperatures, a few simple
rules of thumb can be helpful:
Bernard Knight’s Formula
Body Condition
PMI
Warm and flaccid
< 3 hours
Warm and stiff
3-8 hours
Cold and stiff
8-36 hours
Cold and flaccid
> 36 hours
Algor Mortis
“Death Heat”
“The Chill of Death”
Most useful single indicator of time of
death within 24 hours post mortem
 “Body Cooling”

– Estimated that the body temperature drops
approximately 1.5F/hour

Cooling effected by:
– Location, weather, clothing, activity at death,
victim size
Algor Mortis

To find the standard temperature of a
corpse, a thermometer is inserted into the
liver
– Why the liver? Standard location so
investigators can compare results
Eye Part
Open/Clos
ed
Onset
Corneal film
Open
minutes
Closed
hours
Scleral
discoloration
Open
Minuteshours
Cornea cloudiness
Open
2 hours
Closed
Up to 24
Aqueous Humor
Clear, watery fluid in the eye
 Can measure the amount of potassium
(K+) in the aqueous humor to determine
time of death
 K+ amounts increase for up to 104 hours
after death
 Temperature at time of death effects K+
levels

Stomach Contents
Shows nature of last meal & abnormalities
 Stomach starts to empty within 10
minutes
 If the victim had a…

– Light meal: will stay in stomach 1-2 hours
– Medium meal: will stay in stomach 3-4 hours
– Large meal: will stay in stomach 4-6 hours

Emotional state effects stomach emptying
PMI
Definition
Onset*
Loss*
External Factors
Rigor
Mortis
Muscular
contraction
3-12 hrs
72 hrs
> Temp = > rate of Rigor mortis
< Temp = < rate of Rigor mortis
Livor
Mortis
Pooling of
blood; lividity
/hypostasis
30min 2hrs
6-12 hrs it
becomes
fixed**
Body position, weight, skin color, body
temperature, toxicity
Algor
Mortis
Cooling of body
Ocular
Changes
Corneal Film
Minutes-hrs
Sclera
Discolored
Minutes-hrs
Cornea Cloudy
2-24 hrs
Cornea Opaque
3 days
Light
0.5-2 hours to empty
Medium
3-4 hours to empty
Heavy
4-6 hours to empty
Changes
Stomach
Contents
↑ Temp = ↑ rate of algor mortis
↓ Temp = ↓ rate of algor mortis
Clothing/covering of body will slow the process;
environmental conditions must be considered
Eyes open or closed
Caloric content, age, psychological state/stress
levels, disease, when they last ate, what they
ate, etc.