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Estimating Time of Death. So…. Suspects can be eliminated and focus can be put on others What can be used? Witness statements Body temperature Rigor mortis Lividity Stomach contents Bugs on the body. Defining Time of Death. Estimated – best guess as determined by medical examiner

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slide2
So…
  • Suspects can be eliminated and focus can be put on others
  • What can be used?
    • Witness statements
    • Body temperature
    • Rigor mortis
    • Lividity
    • Stomach contents
    • Bugs on the body
defining time of death
Defining Time of Death
  • Estimated – best guess as determined by medical examiner
  • Legal – the time the body was discovered and pronounced dead (this time is recorded on the death certificate)
  • Physiological – the time the victim’s vital functions actually ceased
time of death continued
Time of death continued…
  • Many deaths are not witnessed – occur in sleep, accidental, suicidal, homicide
  • Example:
    • If a serial killer kills a victim in July, but body isn’t found until October
    • What is the time of death?
      • Physiological – took place in July
      • Legal – October
      • Estimated – could be July, or June or August?
measuring body temperature algor mortis
Measuring Body Temperature – Algor Mortis
  • Normal temp is 98.6 degrees Fahrenheit
  • Body loses heat at a rate of 1.5 degrees per hour
  • Eventually reaches Ambient Temperature – the temperature of its surroundings
  • Varies depending on environment
body temperature continued
Body temperature continued…
  • Liver temperature – reflects true core body temperature
  • If body is found soon after death – more accurate time of death can be assessed
  • What affects body temperature?
    • Obesity
    • Clothing
    • Surrounding temp.
    • Exposure to sunlight
    • Enclosed environment
rigor mortis
Rigor Mortis
  • Stiffening of the body
  • Loss of ATP from muscles
    • Production of ATP depends on supply of oxygen and nutrients
      • ATP is needed to pull the actin & myosin fibers of the muscle apart; therefore, without oxygen, muscles remain contracted
    • Lost when heart stops
    • Causes muscles to contract and stiffen
  • Rigor mortis ends when tissue begins to decompose
@ temp of 70 degrees f
@ Temp of 70 degrees F
  • 2 hours after death rigor mortis is detectable
  • Entire process takes 8 to 12 hours to set in
  • Remains fixed for another 18 hours
  • After another 12 hours muscles relax
  • Therefore can be useful in determining time of death during the first 36 to 48 hours
  • Least effective method of determining time of death because it is extremely variable
fun fact cadaveric spasm
Fun Fact: Cadaveric Spasm
  • Instantaneous onset of stiffness in the body
  • Locked in exact posture it was in moment of death
  • Typically occurs under extremely violent physical or emotional circumstances
lividity
Lividity

Body on back – lividity along back and buttocks

  • Real corpses are less attractive than those portrayed in movies
  • Dark, purplish discoloration of portions of the body
  • Can help determine time of death, and if body was moved
  • Caused by stagnation of blood in vessels
lividity continued
Lividity continued
  • Color provides clues
    • Red or pink reveals high levels of oxygen
      • Caused by carbon monoxide or cyanide poisoning, or cold temperatures
    • Purple color – poor oxygen levels
      • Severe heart failure, shock, or asphyxia
  • Example of how it’s used…
    • Faint areas of fixed lividity along back, darker along the front
      • Body was laying on stomach and moved onto back after 4 to 6 hours
2 processes decomposition
2 processes – Decomposition
  • Autolysis
    • Self-digestion – enzymes of body begin a chemical breakdown of cells and tissue
  • Putrefaction
    • Bacteria destroy the body’s tissue
      • Bacteria of intestinal tract and some environmental bacteria
      • Thrive in warm & moist environments
      • Freezing – stops activities of bacteria
putrefaction is ugly unpleasant
Putrefaction is ugly & unpleasant
  • After 36 hours abdomen, neck, shoulders, and head take on a greenish color
  • Bloating – accumulation of gas from bacteria – begins in face
  • Skin develops blisters where liquid or serum accumulate
  • Skin begins to marble – reveals web-like pattern of blood vessels
  • Abdomen swells, skin continues to blister. Skin and hair begin to slip from body and fingernails start to slough off
  • Body turns a greenish-black and fluids of decomposition leave through mouth and nose.
  • As body swells tissues break open releasing gas and decomposition fluids
decomposition rate
Decomposition Rate

Faster

Slower

  • Obesity
  • Excess clothing
  • Hot & humid
  • Sepsis – blood infection can speed up so 24 hours = 5-6 days
  • Thin
  • Unclothed
  • Cool surface/climate
  • Freezing – can protect body for years
rate of decomposition
Rate of Decomposition
  • Location of body is important:
    • 1 week exposed above ground
    • = 2 weeks in water
    • = 8 weeks in the ground
estimating time of death1
Estimating time of death
  • After a few weeks can be extremely difficult
    • Body temperature, rigor mortis, lividity no longer are of any use
    • Postmortem decay timeline is modified according to conditions
other possibilities
Other possibilities
  • Mummification
    • Bacteria can’t live in dry environments
    • Egyptians used salt and spices to speed drying process so that bodies wouldn’t decay
    • Remain in tact for long periods of time so estimating time of death is difficult, if not impossible
adipocere formation
Adipocere Formation
  • Occurs in wet environments
    • Found in water or warm & wet places
  • Body’s adipose (fat) tissue turns to soap
    • White, greasy, waxy substance
  • Takes 3-6 months to form
  • Mutter Museum - Philadelphia
sinkers to floaters
Sinkers to floaters
  • Body’s dumped in water:
    • Initially sink
    • Rise to surface when gases accumulate because of putrefaction
      • Temperature of water greatly impacts process
    • Warmer water will float after a few days, cooler water may take weeks or months
bodies found in water display
Bodies found in water display:
  • Swollen hands and face after 2-3 days
  • Separation of skin from the body after 5-6 days
  • Loss of fingernails after 8-10 days
  • Floating after 8-10 days in warm water and 2-3 weeks in cold water
stomach contents
Stomach contents
  • Contents of victims stomach help determine T.O.D
  • After meal stomach empties itself in 4-6 hours
  • Food is undigested – death occurred within 1-2 hours of eating
  • If stomach is empty – death likely occurred several hours after eating

Also, varies between people

getting buggy
Getting Buggy…
  • Bugs are usually predictable…But depends on geographic region, locale, time of day, & season
  • Ex: Blowfly
    • Shows up within the first hour
    • Seek moist areas of corpse to lay eggs
    • Nose, mouth, armpit, groin and open wounds favored
    • Eggs hatch to larvae (maggots) with 24 hours
    • Within 12 days adult flies emerge
blowfly life cycle
Blowfly Life Cycle

3rdinstar

Pupa

2ndinstar

Adult

egg

1stinstar

slide27

1stinstar

Adult

Pupa

2ndinstar

Egg

3rdinstar

how can this be used
How can this be used?
  • Find only eggs – death occurred less than 4 hours earlier
  • Fully grown maggots, but no pupae – death occurred less than 10 days earlier
  • Finding pupa indicates that 6-10 days have passed
  • Circumstances can throw off this schedule:
    • Don’t deposit eggs at night
    • Extremely cold conditions – may go dormant
      • Ex: if body is warm during day and cool at night maggots may go through lifecycle during the hot times
      • Entomologist may consult climatologist
what if someone is dead for 3 weeks
What if someone is dead for 3 weeks?
  • Why would this be complicated?
    • Adults produced after ~2 weeks
    • …Lay their own eggs
    • …Follow a similar pattern of life
    • SO – corpse may have eggs, maggots, pupae, and adult blowflies present

YES! …it’s very complicated

Whaaaat?!?

other evidence to estimate t o d
Other evidence to estimate T.O.D
  • Broken watch
  • Victim who missed work for 2 days and is found near his or her front door, dressed in work attire, holding keys, probably heading to work at time of death
  • Victim never showed for a scheduled racquetball game and was found in the garage in exercise clothes likely died while leaving for game
slide31

Using a combination of these methods will help to best determine the most accurate time of death.