Death
Meaning, manner, mechanism,
cause and time
How do we define Death?
• Is a person with a heartbeat alive even if
there is no brain activity?
• Death is a process not an event
– Physiologists; when the heart stops beating,
the cells begin to die
• 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
• Examination of the deceased, Autopsy
• Investigations normally are called upon when the
death is:
– Sudden
– violent
– unexplained deaths
• Investigators will look into
– Manner
– Cause
– And mechanism of death
• Questions sought to answer:
–
–
–
–
Who is the victim
What injuries are present
When did the injuries occur
Why and how were the injuries produced
Forensic Pathology
Autopsy performed to establish cause of death.
Classifications of the manner of Death
*Natural
*Accident
*Suicide
*Homicide
*Undetermined
Manner of Death
• Five ways people die
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
Identify what is the Manner of
Death? Why?
• Case 1: A man with a heart condition is
attacked and dies from a heart attack
during the assault.
• Case 2: An elderly woman dies after
being kept from receiving proper health
care by her son.
Time of Death
Estimating Time of Death
1.
2.
3.
4.
5.
6.
7.
8.
9.
Rigor mortis
Livor mortis: (Lividity)
Algor mortis: Body Core Temperature
Potassium levels in vitreous humor + Clouding
of the cornea
Stomach 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:
• The medical condition that occurs after
death
Results in the shortening of muscle tissue and
the
stiffening of body parts
Body stays in the position they are in when
death occurs
• Begins within 12 hours and ends after 48
hours
After 48 hours, muscle cells begin to autolyse
Rigor Mortis
Time
Event
2-6 hours Rigor begins
After 2
hours
12 hours
Complete Rigor
15-36
Slow loss of rigor,
small muscles first
36-48
Rigor disappears,
Appearance
eyelids, Jaws
stiffen
then center of
body stiffens
Entire body
rigid
Lost in head
and neck, last
is bigger leg
muscles
Figure 49.31 The structure of skeletal muscle
Figure 49.33 One hypothesis for how myosin-actin interactions generate the force for muscle
contraction (Layer 1)
Figure 49.33 One hypothesis for how myosin-actin interactions generate the force for muscle
contraction (Layer 2)
Figure 49.33 One hypothesis for how myosin-actin interactions generate the force for muscle
contraction (Layer 3)
Figure 49.33 One hypothesis for how myosin-actin interactions generate the force for muscle
contraction (Layer 4)
Rigor Mortis
The biochemical cause of rigor mortis is hydrolysis
of ATP in the muscle tissue, the chemical energy
source required for movement. Myosin
molecules devoid of ATP become permanently
adherent to actin filaments and muscles become
rigid.”
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
4. Illness
• Dies with a fever?
• Hypothermic?
What would you expect?
What would you expect?
5. Level of physical activity
• Struggling before death rigor, What would you expect?
6. Sun exposure,
• Sun tanner?
What would you expect?
Estimating Time of Death
1.
2.
3.
4.
5.
6.
7.
8.
9.
Rigor mortis
Livor mortis: (Lividity)
Algor mortis: Body Core Temperature
Potassium levels in vitreous humor + Clouding
of the cornea
Stomach Contents
Evidence of Decompositional Process
Presence/absence of purge fluids
Drying of the tissue
Insect Larval Instars
Livor mortis
* Is a settling of the blood in the lower portion of the
body
** Causing a purplish red discoloration of the skin.
*** Discoloration does not occur in the areas of the
body that are in contact with the ground or another
object,
3. Livor mortis
Autopsy and time of death
cont…
Livor mortis: the medical 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
Estimating Time of Death
1.
2.
3.
4.
5.
6.
7.
8.
9.
Rigor mortis
Livor mortis: (Lividity)
Algor mortis: Body Core Temperature
Potassium levels in vitreous humor + Clouding
of the cornea
Stomach Contents
Evidence of Decompositional Process
Presence/absence of purge fluids
Drying of the tissue
Insect Larval Instars
Potassium levels in vitreous humor
+ 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
Potassium levels in vitreous humor
+ Clouding of the cornea
• Vitreous humor is the jelly like fluid found
in the eye.
– Concentration of potassium increases slowly
during first few days
Vitreous humor
5. Stomach Contents
Stages of Decomposition
• Initial decay
– Corpse appears normal, internal bacterial
decay and autolysis begins
• Putrefaction
– Odor of decaying corpse swollen
• Black Putrefaction
– Very strong odor, flesh appears black, gases
escape, corpse collapses
• Dry Decay
– Corpse is almost dry, further decay slows from
lack of moisture
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
Objective: You will be able to explain how
entomology can be used to determine the time of
death.
Do Now:
• Read “Forensic entomology” on p. 19
• What factors affect the development of
insects?
Forensic entomology
•
•
Entomology is study of insects
Used for a large variety of instances
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–
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Insects and human remains
Damage to property for a civil suit
Insects and injuries in abuse cases
Uses
•
Child abuse cases where parents use
wasps to punish children
•
Neglect and improper care of wounds
of children and elderly
•
Can explain some car accidents or
plane crashes (obstructing fuel lines)
•
Analysis of insects on outside of car
may lead to where car has been
Uses
•
Affect blood splatter when insects like
roaches walk through it and make unusual
marks
– May also carry blood spot to another part
of room which confuses investigators
– Fleas and flies feed on blood and leave
some behind in their wastes
•
Insects can be used to help determine
origin of material like marijuana because
insects feed off of it
•
Insects can be used to determine the time
of death
Life cycles of insects is important to
understand time of death
•
Both follow complete metamorphosis
(egg, larva, pupa, adult)
•
Fly larva are called maggots
•
Determining stages will help tell time of
death
Complete Metamorphosis
Fly Larvae (maggots)
Fly Pupa
Adult fly emerging from pupa
Blowflies are usually the 1st
invader
Can lay eggs within 20
minutes of death
Blowfly
•
The egg is laid in a day by 1 or 2 days a larvae
hatches
After feeding, larvae leaves body to form a
pupa
•
–
–
–
Pupa cases stay behind so presence and number
important
If adult has already emerged then case will look cut
open on one end
Used to determine maximum postmortem
Beetle larvae (Coleoptera)
Coleoptera
•
Coleoptera will invade after most of liquid
part is gone
– Beetle larvae different from fly because it
has 3 pairs of legs and fly has none
– Dermestid beetles clean bones
– Much later in decay process, predaceous
beetles will appear to feed on larvae
Predacious beetles
Entomological evidence can also help
determine the circumstances of abuse and
rape
•
Victims that are incapacitated (bound,
drugged, or otherwise helpless) often
have associated fecal and urine soaked
clothes or bed dressings.
•
This will attract insects that would
normally not appear
Movement of body
•
•
Certain species will lay eggs inside
environment, some outside
Some species prefer sunlight or shaded
environments
Other uses of Insects
•
Can do DNA analysis on the blood that is
in the bodies of these insects that they
ate
•
Can do toxicological analysis on insects
because they may contain poisons in
them from eating the person that had
poison