Time of Death Determination

Livor Mortis

Rigor Mortis

Livor Mortis – Color of Death

• 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 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 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