The Process of death

Chapter 13Forensic Science

Mrs. Morgan

• 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

Confirming Death

• 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

At the crime scene

• 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

Time of DeathAlgor Mortis: Body cooling rate

• Calculating time of death – Glaister Equation

• Used as a starting point to determine time of death – ultimately use other factors to corroborate a more accurate time

98.4°F – internal body temperature 1.5

Hours since death =

Click to edit Master title styleTime of Death

• 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

Changes to the body

Livor Mortis: skin discoloration caused by the pooling of blood

•Starts 30 min – 3 hours after death•Maximum lividity 6 – 12 hours after death

Post-Mortem Lividity

Parts of body touching the ground/surface show no lividity due

to compressed capillaries

Rigor Mortis: rigidity of skeletal muscles

More changes

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…

I don’t know – I googled “rigor

mortis” and this was one of the

top hits…

Overall time of death

• Pathologists will use multiple factors to calculate TOD

• Always a small margin of error

Temperature of body

Stiffness of body Time since death

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

Overall time of death

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).

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).

Dry decay (diagenesis): Cadaver almost dry; slow rate of decay. May mummify (50–365 days).

Stages of Decomposition

All of the changes that accompany decomposition are subject to variation

based on individual characteristics and the

environment

• 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

The autopsy

• 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

Who & why

The tools

Stryker saw – used to cut through the skull to remove

the brainStandard tools used in an autopsy

• Starts with thorough external exam–Physical attributes–Scars and/or tattoos–Evidence of wounds/bruises

–All findings diagramed and recorded in detail

Autopsies – the outside

• 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

Autopsies – the inside

Finishing up

Organs returned to proper place in cavities and

incisions are sewn up

Tissue and fluid samples are taken, analyzed and stored