Transcript document

The Science of Death and Decay
Time of Death
Can estimate time of death from
• body temperature (algor mortis)
estimate: [98.6 oF – rectal temp]/1.5
• insect action (forensic entomology)
• stomach contents (stage of digestion)
• last known activity (last sighting,
newspaper/mail)
• normal postmortem changes
Time of Death
Entomology
Time of Death
Can estimate time of death from
• body temperature (algor mortis)
estimate: [98.6 oF – rectal temp]/1.5
• insect action (forensic entomology)
• stomach contents (stage of digestion)
• last known activity (last sighting,
newspaper/mail)
• normal postmortem changes
Changes After Death
• Decomposition
• Why do we need to know:
– Not to misinterpret these changes
– Help to determine time (place) of death
Normal Postmortem Changes
1. rigor mortis
2. livor mortis
3. desiccation
4. putrefaction
5. cell autolysis (also called butyric fermentation)
6. dry decay
Rigor Mortis
Body warm
not stiff
less than 3 hours
Body warm
stiff
3-8 hours
Body cool
stiff
8-36 hours
Body cool
not stiff
more than 36 hours
Livor Mortis
Desiccation
Putrefaction
Normal Postmortem Changes
1. rigor mortis
2. livor mortis
3. desiccation
4. putrefaction (days 4-10)
5. cell autolysis (days 10-20)
6. dry decay (days 20-50)
Early Changes
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No breathing, no circulation
Fall in blood pressure
Metabolism gradually stops
Loss of neoronal activity
– No reflexes, no corneal reflex, fixed dilated
pupils, eye looses the tension
Early Changes
• Primary Flaccidity: complete loss of tone
• Muscle may be still reactive for hours (focal
twitching)
• Pale skin and conjunctiva
• Face may remain blue/red
• ?? Hair continues to grow
• Loss of sphincter action: pass urine, semen,
regurgitation of food
Rigor Mortis
• Lack of oxygen – no energy – no ATP –
glycolysis – lactic acid – acidic cytoplasm – actin
and myocin bind
• “Stiff Muscle”
• Factors affects Rigor Mortis:
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Level of glycogen
Level of lactic acid
Body built
Temperature, weather
Rigor Mortis
• What is Rigor mortis like if death occurs
after
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exercise,
electric shock,
in infant,
in elderly
In summer
In winter
Rigor Mortis
• Starts in small muscle around eyes and mouth,
jaw, fingers,
• Then spreads from head to legs
• Estimated time of death:
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In face: 1-4 hours
Limbs: 4-6 hours
Increase in strength for the next 6-12 hours
Decomposition starts
Secondary flaccidity from 24-50 hours
Rigor Mortis
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Body feels warm & Flaccid: <3 hours
Body feels warm & Stiff: 3-8 hours
Body feels cold & stiff: 8-36 hours
Body feels cold & flaccid: > 36 hours
Cadaveric Rigidity
• Forensic rarity
• Stiffness of muscle occurring immediately
at time of death
– Finding items in hands
– ?emotional/physical stress at death
Post Mortem Hypostasis
(Lividity)
• No circulation, relaxation of blood vessels
• Blood moves to dependent area
• Positioning of body: supine, prone, on side,
on head, hanging
• Pink-blue color of the dependent area
• May not be apparent in infants, elderly,
anemic
• Difficult to see in dark skin, jaundice
Post Mortem Hypostasis
(Lividity)
• Blanching:
– Around face (not asphyxia)
• Color:
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Pink – deep pink – blue – purple
Cheery pink: in carbon monoxide poisoning
Dark red: in cyanide poisoning
In hypothermia: pink around large joints
• Movement of body and change in lividity!
Cooling of the body after Death
• Physical property
• Assumptions:
– Temperature was 37 at the time of death
– Thermally static environment
Cooling of the body after Death
• Variables:
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Mass of body
Surface area
Body temperature at death
Site of reading
Posture
Clothing
Environment temperature
Winds, humidity, rain
Estimation of the time of Death
• Body temperature
– Rectal, ears, nose, liver
– Henssge’s Nomogram
• Body temperature
• Ambient temperature
• Body weight
• Other methods
– Gastric contents
– Entomologist
– Anthropologist
Decomposition
• Air
• Dry, wet
• Water
Putrefaction
• The most common route of decomposition
• Liquifaction of the soft tissue over time
• The warmer the temperature, the earlier the
process
Putrefaction
• Visible 3-4 days
• Green discoloration in the right iliac fossa
• Marbling of skin: linear branching ptterns
of brown discoloration of skin
• Blistering, skin sloughs off
• Gas formation, swelling of body: face,
abdomen, breast, genitalia
Putrefaction
• Increase internal pressure, protrusion of
tongue, eyes,
• Bloody fluids
• Within a week: body cavity will burst
• Tissue liquify
Mummification
• Dry condition, eg. Dessert
• Drying and leathery body
• Part or whole body
Adipocere
• Wet condition, water
• Chemical change of body fat to waxy
compound material
• Pale, greasy semi fluid material, unpleasant
smell
• Firm waxy compound material: takes weeks
to months to form
Skeletalization
• More quickly to occur on the surface than in
burried body
• Soft tissue will be absent by 2 years
• Tendon, ligaments, hair nails may remain
• By 5 years bone disarticulate
Identification
• Living: coma, amnesia, infancy, mental
defect
• Decomposed body
• Following injury
• Mass disasters
General Morphologic Features
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Appearance
Height, weight
Hair color, length
Beard, moustache
Skin pigmentation
Ethnic background
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Eye color
Clothing, jewellery
Tatoo, surgical scars
Injuries, deformities
Age:
– Estimation
– Ossification center
Fingerprint
• Chance of identical finger print is: 1 in 64
million
• Identical twins
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Teeth
• Identification of person
• Age
• Bite marks
Identification of origin of tissue
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Blood, semen, saliva..
Come from suspect for victem
Match of human remains
Resolve paternity/maternity
Identification of origin of tissue
• DNA profiling:
– Matching
– Paternity, maternity
– Sampling:
• Nucleated cells: wbc, hair root bulb cells, sperms,
buccal smear..
Identification of origin of tissue
• Human Remains
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Are they human
Is it one or more bodies
Sex: skull, pelvis
Age
• Up to 20-25 years, age can be estimated within
couple of years
• >25 years more difficult to estimate