03: Time of Death

Hopefully, these notes will help you as you listen to the podcasts and as you do further research. For more complete infpramtion on any of the forensic sciens topics check out FORENSICS FOR DUMMIES and HOWDUNNIT:FORENSICS

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9-4-18: Criminal Mischief: Episode #03: Time of Death Notes

LISTEN TO THE PODCAST: https://soundcloud.com/authorsontheair/03-timeofdeath

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

B
ody temperature
Rigor mortis
Livor mortis (lividity)

D
egree of putrefaction
Stomach contents
Insect activity

S
cene markers 

BODY TEMPERATURE 

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. 

RIGOR MORTIS 

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.

R
igor begins throughout the body at the same time
Appears first in smaller muscles- face, neck, and hands
Relaxes in same pattern

G
eneral rule for rigor mortis is 12-12-12
Changes due to: activity, body temp, ambient temp,
Cadaveric spasm 

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
Putrefaction—ambient temp/humidity
Internal bacteria—sepsis hastens
Water X2/BurialX4
Ultimately skeletonize
Floaters
Mummification

Adipocere-from chemical process called saponification-reaction between certain bacteria and the body’s adipose (fatty) tissues.

Stomach Contents:

Stomach empties in 2-3 hours—protein, fatty meals
Intestine transient @ 24 hours

Insect Activity

Forensic entomologist

Insects help in two basic ways: Predictable developmental stages (blowfly); succession of insect species
Changed by body location, weather, season, night

Scene Markers

Includes information at the scene or from witnesses or family and friends.

Missed appointments, uncollected mail or newspapers, and dated sales receipts
V
ictim’s clothing—dressed for work, or morning jog

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