Death: Meaning, Manner, Mechanism, Cause and Time

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Death Meaning, Manner, Mechanism, Cause and Time

• Chapter 11

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Death

• Manner of death can be natural, accidental,
  suicidal, homicidal, or undetermined.
• The most common manner of death is natural.
• Mechanism of Death is the specific change in the
  body that brought about the cessation of life

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Determine Time of Death Livor Mortis

• livor mortis
• Process when body decomposes and blood seeps
  down and settles into lower parts of body.

• Lividity
• pooling or settling of blood in tissues after
  death.
• Begins 2 hours after death becomes permanent
  after 8.

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Determine Time of Death Livor Mortis

• Livor mortis can
• Determine Time of Death
• Within 2-8 hours, can press skin and color
  disappears
• Factors affecting lividity
• Ambient temperature, anything that could impede
  flow of blood to area
• Reveal the position of the corpse within first 8
  hours
• If on back, blood will pool along backside
• Reveal if the body was moved
• If moved, may show dual lividity from first
  position and then from second position

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Determine Time of Death Rigor Mortis

• Stiffening of the skeletal muscles after death
• At death, skeletal muscles cannot relax.
• Without oxygen, calcium accumulates in these
  muscles.
• Calcium is used by the body to signal muscle
  contraction, this accumulation signals the
  muscles to contract.
• The muscles become stiff.
• Rigor mortis starts in the head and works its way
  down to the legs.

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Determine Time of Death Rigor Mortis

• 2 -6 hours postmortem (after death), rigor begins
  in the head
• 12 hours postmortem, rigor is complete and
  throughout the entire body
• 15 -36 hours postmortem, the muscle fibers begin
  to dissolve, and softening begins (rigor mortis
  starts to end).
• 36 -48 hours postmortem, rigor ends and is
  relaxed throughout the entire body.
• Figure 11-8 in book

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Determine Time of Death Rigor Mortis

• Factors that affect rigor mortis
• Ambient temperature
• (cold slow rigor)
• The weight of the body
• (obesity slow rigor)
• The bodys clothing or lack of it
• Any illness the person had at the time of death
• The level of physical activity at the time of
  death
• Sun exposure

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Determine Time of Death Algor Mortis

• Cooling of the body after death
• In death a body no longer generates warmth and
  begins to cool down.
• To find the standard temperature of a corpse, a
  thermometer is inserted into the liver.
• Time of death determined by temperature
  calculations is expressed as a range of time.
• Normal body temperature is 98.6F (37C)

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Determine Time of Death Algor Mortis

• Calculations
• First 12 hours after death
• Body cools 0.78 C (1.4 F) per hour
• After 12 hours after death
• Body cools 0.39 C (0.7 F) per hour
• Example
• What is the temperature loss for someone who has
  been dead for 12 hours?
• 0.78 C x 12 hours 9.36 C

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Determine Time of Death Stomach and Intestinal
Contents

• 4-6 hours for stomach to empty contents into
  small intestine
• Another 12 hours for the food to leave the small
  intestine for the large intestine
• 24 hours for the food to leave the large intestine

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Determine Time of Death Stomach and Intestinal
Contents

• Example
• Determine the time of death from the last meal if
  food is found in the small intestine
• Answer Death occurred 4 - 6 hours after the
  last meal

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Determine Time of Death Stages of Decomposition

• Within 2 days
• Cell autolysis begins following death.
• Green and purplish staining from blood
  decomposition.
• Marbling appearance on the skin. Discoloration of
  the face.
• After 4 days
• The skin blisters.
• The abdomen swells.
• Within 6-10 days.
• The corpse bloats.
• Fluids begin to leak from body openings as cell
  membranes rupture.
• The skin sloughs off.
• Eyeballs and other tissues liquefy.

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Determine Time of Death Insects

• Forensic Entomology
• Within minutes of a death, certain insects arrive
  to lay their eggs on the warm body.
• Blowflies are a common example.
• As a corpse progresses through the stages of
  decomposition, other kinds of insects arrive.
• will discuss more in next unit.

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