Transcript Cause, Manner and Mechanism of Death ppt

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?
How do we define Death?
• Death is a process not an event
– Physiologists; when cells begin to die
• O2 levels drop-no Oxygenno ATP
• Basic processes of the body fails
– Nerves, muscles, organs stop working…
• Once enough cellular death occurs life cannot
restart
Forensic Pathologist
• Examination of the deceasedAutopsy
• when the death is:
– Sudden
– violent
– unexplained deaths
• Investigators will look into
– Manner
– Cause
– mechanism of death
• Questions sought to answer:
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Who is the victim
What injuries are present
When did the injuries occur
Why and how were the injuries produced
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
Time of Death
Estimating Time of Death
1.
2.
3.
4.
Rigor mortis-Stiffness of Death
Livor mortis: (Lividity)-Color of Death
Algor mortis: Body Core Temperature
Potassium levels in vitreous humor + Clouding
of the cornea
5. Stomach Contents
6. Evidence of Decomposition
7. Insect
Algor Mortis
• body temperature Normal body
temperature is 370C (98.60F)
• A body loses heat at a rate of 1.40F 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?
Rigor mortis:
• The stiffness begins 2 hours after death
Oxygen is needed for muscle relaxation.
Rigor Mortis
Time
Event
2-6 hours Rigor begins in head
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
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?
Livor mortis
* Lividity -settling of the blood in the lower portion of
the body
*** Discoloration does not occur in the areas of the
body that are in contact with the ground or another
object
Begins 2 hours after death and permanent after 8
hours
3. Livor mortis
Potassium levels
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.
Digestion provides clues
*stomach empties around 4-6 hours after
last meal
*If NO food is in stomach-how long ago
did death occur?
*small intestines empties after approx. 24
hours after last meal
*large intestines empties after approx. 4872 after last meal
Stages of Decomp
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
Butyric Fermentation
-drying,cheesy smell
• Dry Decay
– Corpse is 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
Forensic entomology
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Entomology is study of insects
Used for a large variety of instances
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Insects and human remains
Damage to property for a civil suit
Insects and injuries in abuse cases
Life cycles of insects is important to
understand time of death
* complete metamorphosis (egg, larva,
pupa, adult)
• Fly larva are called maggots
• Determining stages will help tell time of
death
Complete Metamorphosis
Fly Pupa
Adult fly emerging from pupa
Blowflies are usually the 1st
invader
Can lay eggs within 20
minutes of death
Other uses of Insects
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Can do DNA analysis on the victim
ingested by insect
Can do toxicological analysis
Wound location
Types of Injury
• Antemortem-before death. Signs of
healing
• Perimortem-near time of death. No healing
• Postmortem-after death. Discolored
(bite marks, crushing)