Establishing Time of Death


• Rate: Measures changes in the body by a process that takes place at known rates.

• Rigor, Algor, and Livor Mortis

• Concurrence: Compares the sequence of events that took place at known times with the time of occurrence of the event under investigation.

• A wristwatch stopped by a blow during an assault.

• The extent of digestion of the last known meal.

Rigor Mortis: Stiffness of Death

• Classic marker of death

• Rigidity of the body

• Produced by metabolic (chemical) changes

• More rapid in small muscles

• Heat accelerates – Cold decelerates

• Full Rigor: 6-24 hours, 12 average

• Very subjective (depends on experience)

• Scientifically Unreliable

Algor Mortis: Temperature of Death

• Body temperature is a narrow range (not fixed).

• Illness, decomposition, infection, and absorption of heat can raise body temperature.

• Many formulas to determine TOD.

• Clothing, bodies of water, fatness, ventilation, age, weather conditions.

• Rectal or liver temperature needed.

Livor Mortis: Color of Death

• Setting of blood to dependent parts of the body.

• Cardiac activity stops, and hydrostatic pressure of the blood no longer keeps the blood vessels open.

• Hydrostatic Pressure: The pressure exerted by blood on walls of blood vessels, keeping them open.

• Color depends on skin pigment and additional compounds in the blood (e.g. carbon monoxide).

• Generally dark blue/purple.

• Body areas touching the ground will be blanched (white).

• Usually reaches maximum appearance 8-12 hours.

Dependent vs Fixed Lividity

• Dependent: Just after death, blood flows to the dependent parts of the body and settles.

• Lowest parts of the body due to gravity.

• Fixed: After a period of time, the blood becomes fixed in its location and will not move (even if the body is moved).

Patterned Livor Mortis

• Can give class evidence of where the person died and was laying.

• The lividity is consistent with the position of the body.

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