Postmortem Events

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Postmortem Events

• Stephen D. Cohle, MD
• Spectrum Health

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Window of time

• Last known alive found dead

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Rigidity (rigor mortis)

• Definition hardening of muscles due to lactic
  acid accumulation and gelatinization of
  myofibrillar protoplasm.
• Onset 2-4 hours, complete at 12 hours, reversal
  at 24-36 hours
• Onset hastened by fever, convulsions, vigorous
  activity, hot environment

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Rigidity continued

• Delayed by rapid cooling
• Disappearance 9-12 hrs in hot environment or
  sepsis
• Incomplete in those with little muscle mass
  (young, old, cachexia)
• Useful to determined whether body moved postmortem

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Rigor mortis

• false rigor occurs in extreme cold from
  freezing of body fluid and solidification of
  subcutaneous fat
• Fire deaths
• Marked muscle shortening (pugilistic attitude) in
  severe burning secondary to greater mass of
  flexor muscles compared with extensors

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Livor mortis(hypostasis, suggilation)

• Definition settling of blood to dependent
  portion of body caused by gravity
• Absent in areas of pressure
• Normally dark red or purple cherry red with CO
  or cold environment DT retention of oxyhemoglobin
• Cyanide dark blue to pink, methemoglobin brown

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Livor mortis continued

• First apparent at 2 hours, well developed at 4
  hrs, maximum at 8-12 hours
• Fixed after 8-12 hours
• Distribution in nondependent areas indicates
  postmortem moving after establishment of livor
• Occurs in organs, may simulate pulmonary
  congestion or intestinal infarct

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Livor mortis continued

• Artifact postesophageal hemorrhage at level of
  larynx, occurs from marked congestion leading to
  hemorrhage in loose tissues of the esophagus
  adjacent to anterior longitudinal ligament of
  cervical spine.
• Arises from veins and venous plexus in front of
  spine.

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Body cooling(algor mortis)

• Rules of thumb
• 1.5F/hr for first 12 hrs of core temperature
• Variables altering estimate of postmortem
  interval
• Initial body temperature, body dimensions, body
  posture (fetal position preserves heat better
  than spread eagle position)
• Environmental temperature, convection,
  conduction, radiation, medium around body, e.g.
  water.
• Nutritional status relative humidity

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Rules of thumb

• Body outdoors feels cold on exposed areas in 2-4
  hrs
• Body indoors feels cold in protected areas in 6-8
  hrs

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Time of death

• Time of death spot check (Knight)
• Warm and flaccid dead lt 3 hrs
• Warm and stiff dead 3-8 hrs
• Cold and stiff dead 8-36 hours
• Cold and flaccid gt 36 hrs

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Food in the stomach

• Accuracy depends on knowledge of decedents
  eating habits meal times, quantity of last meal,
  interval between last two meals
• Light meal 1.5-2 hrs
• Medium meal 3-4 hrs
• Heavy meal 4-6 hrs from stomach to duodenum
• (head) of the meal reaches cecum 6-8 hrs
  postprandial

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Food in stomach continued

• Speed of transit liquids gt semisolids gt solids
• Water with meal hastens exit
• Alcohol and fatty foods delay exit
• Stress usually delays emptying

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Food in stomach continued

• Composition of contents can be related to last
  known meal
• Strain and wash gastric contents to identify food
  types

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Postmortem chemistry

• Vitreous potassium most commonly studied
• Potassium increases at a rate between .14 and .19
  mEq/hr
• Postmortem potassium shows extreme variability

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Postmortem entomology

• Fly eggs may be deposited at time of death
• First instar larvae 1-3 days, continue to grow
  over next 3-12 days
• Pupae identified at 3-10 days
• First emergence of adult flies at 10 days

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Postmortem entomology continued

• Collect representative number of maggots and
  pupae in 80 alcohol
• Identify site of collection
• Note outside temperature and temperature of
  corpse near collection
• Note temperature of maggot mass

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Decomposition

• Autolysis postmortem changes caused by digestive
  enzymes
• Putrefaction changes caused by bacterial
  activity particularly Clostridium welchii and
  coliforms. These cause gas production and skin
  slippage
• Advanced stages usually start at 36-48 hrs but
  can be hastened by high environmental temperature
  and external injury

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Decomposition continued

• 1st change green staining of right lower
  quadrant of abdomen, 24-36 hrs red discoloration
  of veins (marbling) 4-7 days (caused by gas
  formation and hemolytic) green color caused by
  hydrosulfide and sulfated methemoglobin.
• Skin slippage, blistering, 3-4 days
• Purging of body fluids in about one week

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Decomposition continued

• Mummification
• Desiccation of body in dry environment
• Bacterial putrefaction halted
• Skin becomes leathery, hardened and shriveled
• Terminates in powdery disintegration
• Onset in extremities in 2-3 days, remainder of
  body in several weeks

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Rule of thumb

• One week in air 2 weeks in water 8 weeks in
  soil

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Adipocere formation

• Whitening, waxiness, and stiffening of body fat
• Occurs in cool, moist soil or water
• Takes place 3-5 months postmortem

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Adipocere formation (Dix)

• 4 cases in November/December in Missouri
• Water temperature 43-55 F
• Adipocere begins at 4 months, complete at 10
  months
• Caused by hydrogenation of unsaturated oleic acid
  to hard, opaque steric acid
• Associated with Clostridium welchii

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Skeletonization

• Usually occurs 1-3 years in temperate climate,
  may occur within months

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