Mid-Unit Assessment: Death & Decomposition

K. Williams

Biological death

All organs are ceasing to function.

• Livor, rigor or algor mortis

• Injuries not compatible with death

  • Decapitation

• Decomposition

Brain death

Brain functions are permanently terminated.

• Coma

• No spontaneous breathing

• Pupils will be unresponsive to light

• No reflexes

Manner of Death (MOD)

Way in which a person dies.

• Natural - failure of body functions due to age/disease

• Suicide - purposeful killing of oneself

• Accidental - unplanned events (i.e. car accident or falling from a ladder)

• Homicide - someone else ends the life of another

• Undetermined - recorded on the death certificate

Cause of Death (COD)

Reason someone dies.

• Disease, physical injury, bludgeoning, etc.

Mechanism of Death

Specific change in the body that brought about the cessation of life

• Cardiac arrest, pulmonary arrest, exsanguination (loss of blood)

Initial Decay

Occurs 0-3 days after death.

• The outside of the body appears fresh

• Bacteria in the intestines start to feed on the intestines themselves

• Digestive enzymes breakdown the organs

• Introduction of insects

Putrefaction

Occurs 4-10 days after death.

• Bacteria breaks down tissues and cells, releasing body fluids into cavities

  • Also produces gases which insects are attracted to

Black Putrefaction

Occurs 10-20 days after death.

• Body collapses, fluid drains from the body

• Flesh decomposes and exposed skin turns black

Butyric Fermentation

Occurs 20-50 days after death.

• Remaining flesh is removed and dries out

  • Produces butyric acid

• Body grows mold (in contact with the ground)

• Flies consume the flesh while the beetles feed on skin and ligaments

Dry Decay

Occurs 50-365 days after death.

• Decay occurs very slowly

• Hair disappears, leaves only the bones

Livor Mortis

“Death color,” purplish discoloration of lower skin areas by gravity pulling stagnant blood downward.

• Red blood cells spill hemoglobin (w/o oxygen) turns deep purple

• Fixed lividity is set after 8 hours

• Dual lividity - corpse was moved postmortem

• Colder temperature extends time-frame

Rigor mortis

Stiffening of the muscles.

• Muscle contractions are due to calcium ions into muscle fibers

  • Without oxygen, the calcium accumulates which locks the actin and myosin fibers in a permanent contraction until autolysis breaks down cells

Stages of rigor mortis

Factors influencing time: exercise, warm clothing, surrounding temperature.

• 2-6 hours: eyelids, jaw, moving down the body

• 12 hours: entire body is completely rigid

• 15-36 hours: loss of rigor, head muscles relax first

• 36-48 hours: complete rigor disappearance

Algor mortis

Gradual loss of heat, equilibrium to the surrounding temperature.

• Timeline:

  • 12 hour before death: 1.4 degrees Fahrenheit per hour

  • After 12 hours postmortem: 0.7 degrees Fahrenheit per hour

• Calculations:

  • 1: calculate total temperature loss (98.6 - total heat of the individual)

  • 2: calculate maximum heat loss the individual could experience (12 hrs x 1.4 degrees Fahrenheit)

  • 3: calculate additional hours after 12 hrs

    • Ex. 4.9 degrees / 0.7 degrees = 7.0 hours