Unit 2 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

Insect Presence: Blowflies arrive, followed by ants and wasps.

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

Insect Presence: Beetles arrive due to the gas.

Black Putrefaction

Occurs 10-20 days after death.

• Body collapses, fluid drains from the body

• Flesh decomposes and exposed skin turns black

Insect Presence: Maggots and bacteria break the skin, odors attract more insects (20% of original body weight).

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

Insect Presence: Moths and beetles (10% of original body weight).

Dry Decay

Occurs 50-365 days after death.

• Decay occurs very slowly

• Hair disappears, leaves only the bones

Insect Presence: None, molted larval/pupal cases are left behind.

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

Insect Succession

1. Flies - blowflies, houseflies, etc.

2. Ants and Wasps - predators of flies

3. Beetles - clown beetles, Surinam carrion beetles, etc.

Postmortem Interval (PMI)

Time since death.

Factors affecting development:

• Temp and environmental conditions

  • Warmer temp. increases growth rate (decreases ADH)

    • ADH: Accumulated Degree Hours

  • Colder temp. decreases growth rate (increases ADH)

• Ingested Drugs

  • Cocaine increases growth rate

  • Arsenic decreases growth rate

Entomological Processes of a Crime Scene

1. Death-scene observations

2. Collection of meteorological data (weather)

3. Two collections: live samples of insects (to track growth stages) and preserve other insects from the body

4. After body removal: collect insects from the surrounding soil

Rokitansky Method

Removal of all organs at once in an autopsy.

Steps of an Autopsy

1. External Examination: forensic pathologist notes details including clothing, tattoos, scars, etc.

2. Internal Examination: Y-Incision and organ reveal

3. Organ Removal & Weighing: Rokitansky method, observation of organ health (possible abnormalities or trauma), collect tissue samples

4. Laboratory Testing: toxicology reports

5. Final Documentation: incisions are sewn and the report is compiled

Blowfly Life Cycle

Life Stages: constant of 70 degrees Fahrenheit

• 1st stage: larva - 23 hours

• 2nd stage: larva - 27 hours

• 3rd stage: larva - 22 hours

• 4th stage: pupa - 130 hours

  • Stays Pupa for 143 hours before becoming an adult fly