Download Death Determination

Manner, Mechanism, Cause and Time
of
Death
How do we define Death?
• Death - An individual who has sustained either
(1) irreversible cessation of circulatory and
respiratory functions, or (2) irreversible cessation
of all functions of the entire brain, including the
brain stem is dead.
• Death is a process not an event
– Physiologists; when the heart stops beating,
the cells begin to die and:
• O2 levels drop
• Basic processes of the body fails
– Nerves, muscles, organs stop working, Stoppage
• Once enough cellular death occurs life cannot restart
Forensic Pathologist
a sub-specialty of pathology that focuses on determining the cause of death by examining a
corpse.
• Autopsy - a postmortem examination to discover the cause of
death or the extent of disease.
• Autopsy's are normally are called upon when the death is:
– Sudden
– Violent
– Unexplained
• Investigators will look into
– Manner
– Mechanism
– Cause
– Time
Manner of Death
1. Natural
• Interruption and failure of bodily function resulting
from age or disease
2. Accidental
• Unplanned event
3. Suicidal
• A person purposely kills oneself
4. Homicidal
• Death of one person caused by another
5. Undetermined
• Suicidal or accidental
– Pills, guns
Mechanism of Death
The physiological dysfunction that results in the death.
Example: death due to the gunshot wound, the mechanism is
exsanguination (extreme blood loss).
Cause of Death
The disease or injury that produces the
physiological disruption inside the body resulting in
death.
Example: a gunshot wound to the chest.
Estimating Time of Death
1. Algor mortis: reduction in body temperature following
2.
3.
4.
5.
6.
7.
8.
9.
death
Rigor mortis: stiffening of the body after death
Livor mortis: (Lividity) : settling of the blood in the
lower portion
Potassium levels in vitreous humor + Clouding of the
cornea
Digestive Contents
Evidence of Decompositional Process
Presence/absence of purge fluids
Drying of the tissue
Insect Larval Instars
Algor Mortis
• Uses body temperature to determine time
of death
• Normal body temperature is 370C (98.60F)
• A body loses heat at a rate of 1.40C per
hour until the ambient temperature is
reached
– Rate varies according to environmental
temperature
• Once ambient temperature is reached, you
cannot use this method to determine time
of death
Question: What are some Factors
that would affect Algor Mortis?
•
•
•
•
Ambient temperature
Wind?
Excess body fat?
Clothing
Rigor Mortis
Time
Event
Appearance
2-6 hours
Rigor begins
eyelids, Jaws
stiffen
After 2 -6
hours
then center of
body stiffens
12 hours
Complete Rigor
Entire body rigid
15-36
Slow loss of rigor, small
muscles first
Lost in head
and neck, last is
bigger leg
muscles
36-48
Rigor disappears,
muscles become relaxed
What are some factors affecting Rigor mortis ?
1. Ambient temperature,
• Cooler the body the slower the onset of rigor
2. Person’s weight
• Fat stores more oxygen and slow rigor
3. Type of clothing
• Helps keep the body warm
3. Livor mortis
Livor mortis
the condition that occurs after death and results in the
settling of blood in areas of the body closest to the
ground
– Evident 30-120 minutes postmortem
– 8-12 hours (24-36 hours in cooler temps) postmortem- maximum
color or “fixed” livor mortis due to hemolysis (blood vessels break
down)
– May occur antemortem (before death) in slow deaths
– Can congest internal organs
– Discoloration does not occur in the areas of the body that are in
contact with the ground or another object
–
Clouding of the cornea
• Cornea is the clear covering of your eyes
– Becomes cloudy and opaque after death
• Takes only a few hours after death if eyes are
open at death
• It takes 24 hours if eyes are closed at death.
Cornea
Digestive Contents
• Stomach empties contents after 4-6 hrs
• Small intestine empties after 24 hrs
• Colon empties 24-48 hrs
Stages of Decomposition
• 2 days
– Cells autolysis
– Greenish purple staining occurs, blood decomposing
– Skin takes on Marbled Appearance
• 4 days
– Skin blisters
– Abdomen swells with carbon dioxide
• Due to bacteria in intestines
• 6-10 days
– Corpse bloats with CO2
– Corpse eventually bursts
– Fluid begins leaking from openings as cell
membranes rupture
– Eyeballs liquefy
– Skin sloughs off
Forensic entomology
•
Entomology is study of insects
Life cycles of insects are used to
determine time of death
•
•
Complete metamorphosis
adult, egg, larva (maggot), pupa, adult
Complete Metamorphosis
72 hrs
50 hrs
23 hrs
35 hrs
130 hrs
143 hrs
Blowflies are usually the 1st
invader
Can lay eggs within 20
minutes of death
Beetle larvae
Predacious beetles