1) Determining time of death involves measuring the body's temperature, the presence of rigor mortis, livor mortis, and decomposition. 2) An autopsy is performed by a pathologist to determine cause and manner of death and may involve external and internal examination of the body and collection of tissue samples. 3) The stages of decomposition include initial decay, bloating, black putrefaction, butyric fermentation, and dry decay over many months.

1. The Process of
death
Chapter 13
Forensic Science
Mrs. Morgan

2. Confirming Death
• Although it may be obvious,
any death must be confirmed
by a trained professional –
usually a doctor, coroner or
medical examiner
• Must meet the criteria of death
– then pronounced dead
• Body can then be moved,
handled and processed if
necessary

3. At the crime scene
• A dead body found at a crime
scene is handled and processed
by the medical examiner’s office
• Officers and CSIs cannot touch
or move the body until the ME
has given permission to do so
• Any evidence on a body is
collected by the ME staff and
turned over to the crime lab

4. Time of Death
Algor Mortis: Body cooling
rate
• The body slowly cools once the
heart stops beating
• Measuring body temperature can
approximate the time of death
• Use liver temperature
• Can be influenced by the
environment or internal
conditions

5. Click to Time of Death
edit Master title style
• Calculating time of death – Glaister Equation
Hours since death = 98.4°F – internal body temperature
1.5
• Used as a starting point to determine time of
death – ultimately use other factors to
corroborate a more accurate time

6. Changes to the body
Livor Mortis: skin discoloration
caused by the pooling of blood
• When heart stops beating,
blood pools and coagulates
in lower portions of the body
due to gravity – creates
red/purple blotches
• Can show the position of
body after death
• May indicate if the body has
been moved or repositioned

7. Post-Mortem Lividity
•Starts 30 min – 3 hours after death
•Maximum lividity 6 – 12 hours after death
Parts of body touching the
ground/surface show no lividity
due to compressed capillaries

8. More changes
Rigor Mortis: rigidity of skeletal
muscles
In humans:
•starts after about 3 hours
•reaches maximum stiffness
after 12 hours
•gradually dissipates until
approximately 72 hours
after death. I don’t know – I googled
“rigor mortis” and this
was one of the top hits…

9. Overall timetime death
Overall of of death
• Pathologists will use multiple factors to
calculate TOD
• Always a small margin of error
Temperature of
Stiffness of body Time since death
body
Warm Not stiff Not dead more than 3 hours
Warm Stiff Dead between 3 and 8 hours
Cold Stiff Dead between 8 and 36 hours
Cold Not stiff Dead for more than 36 hours

10. Stages of Decomposition
Initial or fresh decay
(autolysis): The cadaver appears
fresh but is decomposing internally
due to the activities of bacteria
present before death (0-4 days).
Putrefaction or bloating: The
cadaver is swollen by gas produced
internally, accompanied by the
odor of decaying flesh (4–10 days).

11. Stages of
Decomposition
Black putrefaction: Flesh of
creamy consistency, with exposed
body parts black. Body collapses as
gases escape. Fluids drain. Odor of
decay very strong (10–20 days).
Butyric fermentation: Cadaver
drying out. Some flesh remains at
first; cheesy odor from butyric acid
(20–50 days).

12. Stages of Decomposition
Dry decay (diagenesis):
Cadaver almost dry; slow rate of
decay. May mummify (50–365
days).
All of the changes that accompany
decomposition are subject to
variation based on individual
characteristics and the environment

13. The autopsy
• Performed to determine
cause and manner of death,
discover the extent of disease
or for teaching purposes
• Forensic autopsies have legal
implications
• Performed by a pathologist –
specially trained MD

14. Who & why
• ME can order an autopsy
• If not – need permission from next
of kin
• Autopsied people include
– Suspicious deaths
– Not under the care of a doctor
– Died during an operation
• Family can limit scope or request
specific procedures be followed

15. The tools
Stryker saw – used to cut
through the skull to
remove the brain
Standard tools used in
an autopsy

16. Autopsies – the outside
• Starts with thorough external
exam
– Physical attributes
– Scars and/or tattoos
– Evidence of wounds/bruises
– All findings diagramed and
recorded in detail

17. Autopsies – the inside
• Body is open with a Y-incision
to expose the thoracic and
abdominal cavities
– Shoulders to pubic bone
• Ribs are cut to expose the heart
and lungs
• Organs are removed, weighed
and examined

18. Finishing up
Tissue and fluid samples are
taken, analyzed and stored
Organs returned to proper
place in cavities and
incisions are sewn up