Criminal Mischief: Episode #03: Time of Death Notes
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The ME’s 3 most important determinations: Cause, Manner, and Time of Death
Part II: Time of Death Notes
DETERMINATION OF THE TIME OF DEATH
Determining TOD is critical
Both an art and a science
The sooner after death the more accurate the estimate
Changes death variable and unpredictable.
Physiologic TOD, Estimated TOD, Legal TOD
Always a best guess
None of the methods are very accurate
Livor mortis (lividity)
Degree of putrefaction
Normal body temperature is 98.6F
Body loses or gains heat until it equilibrates with that of the surrounding medium.
The formula is: Hours since death = 98.6 – corpse core temperature / 1.5
Cold/wind/water increase heat loss
Obesity, heavy clothing, warm still air, exposure to direct sunlight, and an enclosed environment slow heat loss.
Spasm due to chemical reactions within the muscle cells after death.
Loss of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) causes the muscles to contract and stiffen.
Later loss of rigidity from the putrefaction process.
Rigor begins throughout the body at the same time
Appears first in smaller muscles- face, neck, and hands
Relaxes in same pattern
General rule for rigor mortis is 12-12-12
Changes due to: activity, body temp, ambient temp,
LIVOR MORTIS (Lividity)
Purplish—exceptions for CO (carboxyhemoglobin), Cyanide (cyanohemoglobin), Freezing
Dependent areas—lying, sitting, hanging
Pale support areas
Gravity, then leaking into tissues
Shifting vs Fixed—Onset 1/2 to 2 hours/fixed by 8 hours
Mismatch of pattern and body position
THE RATE OF BODY DECAY
Time Since Death
Internal bacteria—sepsis hastens
Adipocere-from chemical process called saponification-reaction between certain bacteria and the body’s adipose (fatty) tissues.
Stomach empties in 2-3 hours—protein, fatty meals
Intestine transient @ 24 hours
Insects help in two basic ways: Predictable developmental stages (blowfly); succession of insect species
Changed by body location, weather, season, night
Includes information at the scene or from witnesses or family and friends.
Missed appointments, uncollected mail or newspapers, and dated sales receipts
Victim’s clothing—dressed for work, or morning jog
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