Transcript Time of Death Determination

Time of Death Determination
Livor Mortis
Rigor Mortis
Livor Mortis – Color of Death
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Settling of blood after death
Gravity causes blood to settle at lowest spot
Apparent 20 minutes – 4 hours after death
Not “fixed” (non-changing) for ~ 3 hrs
(blanching upon finger pressure)
• 6-8 hrs will be fixed
Variables to Consider
• Bodies in water, etc. where no fixed
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position
Situations w/o gravitational effect
(spacecraft murder?)
Decomposition
Suntan/dark skin
Anemia
Massive loss of blood
Visual Appearance
• Usually dark red or purple
• Carbon monoxide poisoning, cyanide
results in cherry red or pink appearance
• Likewise exposure to cold will affect
Rigor Mortis – Stiffness of Death
• Chemical changes after death cause muscle
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tightening
Starts in small muscles and moves to larger
Muscles of face and jaw usually go first
3 hrs. – no effect
4-6 – neck and jaw
6-8 – more advanced throughout body
Rigor Mortis
• 12 hrs – full rigor
• 18-24 hrs – begins resolving, head and jaw
are slack
• 30 hrs – rigor resolved, body limp
Rigor Mortis
• Chemical changes involve accumulation
and breakdown of adenosine triphosphate
(ATP)
• ATP is the facilitator of muscle movement
• When ATP depleted, full rigor results
• Loss of rigor due to muscle fiber
decomposition
Rigor Variables
• Muscular individuals experience to higher
degree
• Antemortem activity can deplete ATP and
speed up onset
• Death in sleep can slow down due to more
ATP at death
Cadaveric Spasm – a Rarity
• Onset of rigor is instantaneous but
diminishes in normal manner
• Brought on by sudden, violent impact such
as instantly fatal gunshot wound or collision
• Happens but extremely rare