Forensic Pathology III

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Forensic Pathology III

• Dr. Elizabeth Gardner

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Time of Death

• Rigor Mortis
• Livor Mortis
• Algor Mortis

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Blunt Trauma

• Contusions
• Black and Blue marks
• Abrasions
• Scrapes
• Lacerations
• Split versus cut
• Indications of Blunt Trauma

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CUTTING AND STABBING

• CUTTING (INCISED) WOUNDS
• sharp instrument
• longer on the skin surface than it is deep
• Edges of the wound are sharp
• not usualy ragged or abraded
• Surrounding skin is usually undamaged.
• No tissue bridges
• Slicing

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Stabbing Wounds

• Deeper than wide
• The size of skin defect ? depth
• Ends of the stab wound angles.
• May be blunt or sharp,
• Single-edged blade 1 blunt angle and 1 sharp
  angle
• Double-edge knives 2 sharp angles
• Homemade sharpened weapons sharp or dull angles.

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Size of the Weapon

• The width and length of a weapons blade
• May be determined by analyzing a stab wound
• A 0.5-wide blade may cause a 0.5-wide external
  wound
• Knife is inserted and removed straight
• Victim or assailant moves - Entrance wound may be
  longer
• External wound may also be slightly shorter ?
  skins elasticity
• Depth of the wound track may gt the length of the
  blade
• Skin and surrounding tissues will collapse
• Spring back as the pressure is relieved

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Size of Wound?
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ID of the Weapon

• Rarely is the weapon discovered in the wound
• Matching the weapon to a wound
• Tip of the blade breaks off
• Can be matched to the weapon

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Single-edged Knife

• Light arrow blunt angle
• Dark arrow sharp

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Multiple Incised and Stab Wounds

• Defense wounds
• Multiple incised and/or stab wounds of the neck,
  face, and extremities
• Usually caused by an assailant
• Suicide
• Multiple incised wounds of neck or wrists
• Varying depths on the suggest a suicide.
• Hesitation marks and are characteristic
• Overkill
• A body sustaining tens or hundreds of stab and
  incised wounds
• Highly emotional setting
• Sex
• Drugs

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What Do These Wounds Indicate?
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Defense Wounds

• What type of Wounds?
• How were they caused?

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Some Wounds Can be Caused by Treatment

• Lower two wounds were caused by thoracotomy
  incisions to drain blood from the chest

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Internal Damage

• Heart single-edged blade
• Multiple stab wounds in left lung and ribs
• 10 stab wounds in large incision

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Head Trauma

• Contusions, lacerations, and abrasions
• Obvious external signs are not necessary
• Occasionally, the weapon leaves a characteristic
  identifying pattern on the scalp
• Exception rather than the rule.
• Battles sign
• bluish discoloration of the skin behind the ear
• blood leaking under the scalp after a skull
  fracture.
• Spectacle hemorrhage (raccoons eyes)
• Discoloration of the tissues around one or both
  of the eyes
• Due to a fracture of the skull
• May be mistaken for blows to the face and eyes.
• Blow to the head ? bleeding under the scalp
• May be skull fractures
• ID weapon or type of instrument

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• Battles Sign Spectacle hemorrhage

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Fell Down the Stairs

• multiple areas of subscalpular hemorrhage
• Series of blows to the head

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There May be More than One Fracture

• Many fractures indicate more than one blow
• Need definable points of impact to determine the
  number of blows

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Cerebral Contusion

• Focal brain injury is an injury
• Region, system, or side of the brain
• Most common type of focal brain injury is a
  cerebral contusion
• Bruise in the brain that consists of a
  superficial focus of brain hemorrhage, necrosis,
  and/or laceration.

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Coup contusion

• Part of the brain receiving the focus of an
  impact
• Contusions and lacerations caused by heavy weapon

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Contrecoup Contusion

• Areas of the brain remote from the focus of
  impact
• Brain bounces off opposite side of skull

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Cause of Death Subdural Hemorrhage

• Subdural hemorrhage is blood under the dura
• tough membrane that covers the entire brain and
  spinal cord
• It originates from ruptured veins
• May not be an associated fracture of the skull.

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Firearms Hand Guns and Rifles

• Primer stable, but shock sensitive
• Gunpowder or propellant volumes of gas
• Bullet or projectile

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Gunpowder

• Soot or fouling
• Completely burned gunpowder
• can be washed off the skin
• tattooing or stippling.
• Particles of burning and unburned powder
• Become embedded or abrade in the skin

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What was the Range Tight Contact

• All gunpowder residue on the edges or in the
  wound
• Searing or burning of wound margins
• Reddening of surrounding skin due to carbon
  monoxide (CO) gas produced by burning powder
• Tearing of the skin around the entrance wound
  (especially in head wounds)
• because of pressure buildup and blow-back of the
  skin toward the muzzle.

Splitting Due to Gases
Reddening Due to CO
Muzzle Blow-back
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Loose contact

• Gunpowder deposited around the edges of a wound

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Close range

• muzzle-to-target distances of approximately 612
• Both fouling and stippling are present

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• Intermediate range
• muzzle-to-target distances of approximately 12
  to 3
• No fouling, only stippling or deposition of
  particles on clothing
• Distant wounds No fouling or stippling.

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Significance of Amount of Gunpowder Present

• Different among weapons
• Different in same weapon with different
  ammunition
• To make a comparison
• Test-fire gun in question
• Same ammunition
• The scene must be examined for bullets and
  cartridges.
• Bullets may be under the body or caught in
  clothing after exiting the body.

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Entrance and Exit Wounds

• Generally easy to differentiate (for the expert)
• Entrance wounds
• Circular defects with a thin rim of abrasion
• Entrance wounds of the face atypical
• Surfaces are not flat.
• Exit wounds
• More often irregular in shape
• Slitlike
• Ragged edges
• No Rim of abrasion unless victum is against
  another object
• shored
• Skin around discolored because of underlying
  bleeding in the soft tissues.
• May be circular like entrance wounds

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Entrance and Exit
On the left Entrance Wound On the right Exit
Wound Note beveling
Two Exit Wounds with Hemorrhage
Entrance and Exit Wounds Shot in chin as going
up stairs
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Shotgun Injuries

• Different components
• Gunpowder
• Pellets sometimes slug
• Wad
• The range (distance) of fire more easily
  determined
• Presence or absence of pellet spread
• Same gun and ammunition

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Shotgun Wounds
Shot by police from across a yard Three pellets
entered the heart
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ASPHYXIA (SUFFOCATION) AND DROWNING

• Asphyxia means death due to lack of oxygen to the
  brain
• Compression of the neck (hanging and
  strangulation)
• Blockage of the airway (suffocation, gagging)
• Compression of the chest, neck, or face
• Postural or positional asphyxia
• Chemical or lack of available oxygen

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Compression of the neck

• Occlusion of the vasculature In hanging (usually
  suicide), the neck can be compressed
• Not necessarily the airway (larynx or trachea)
• Very little pressure is needed
• Hanging
• Throttleing
• Unconscoious in seconds to over a
• Pressure must be continued in order to cause
  death.

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Signs of Trauma to the Neck

• Contusions or abrasions, rarely lacerations
• Abraded, imprinted mark
• Thin ligature pattern can can be matched to the
  particular ligature
• Wide ligature no specific pattern
• Superficial fingernail cuts from either the
  victim or assailant
• Pinpoint hemorrhages, or petechiae
  (pet-TEA-key-eye)
• Eyes, lids, face
• buildup of vascular pressure which causes
  capillaries to rupture
• Not often found in suicidal hanging
• May occur in sudden natural death
• Tardieu spots
• Ruptured blood vessels in the tissues after
  prolonged hanging, especially in the lower
  extremities,

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Ligature Marks
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Petechiae
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Tardieu spots

• Lower extremities

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Blockage of the airway

• Suffocation, aspiration, gagging
• Airway is blocked
• A pillow or hand placed over the mouth
• Un-chewed food or small parts of toys lodged in
  an infants or childs airway
• Individuals without teeth or with a history of
  stroke or other debilitating disease may have
  trouble chewing and aspirate food into the
  airway.
• Those under the influence of alcohol are also
  more likely to aspirate
• Usually no signs of trauma

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Car Fell Off Cement Blocks
Pressure on neck caused Extreme petechiae
(pet-TEA-key-eye)
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Postural or Positional Asphyxia

• Compression of the chest, neck, or face
• person cannot breathe because of an inability to
  move ones chest
• Airway is compressed against the neck or face
• Commonly seen during motor vehicle accidents
• when the vehicle overturns on a victim
• driver trapped between the steering wheel and
  seat
• Signs of Trauma
• Few injuries
• Blunt trauma
• Petechiae of the eyes and face

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Alcoholic Fell Asleep with Head on Pillow

• His nose and mouth were occluded by the pillow
• autopsy showed only signs of alcoholism
• Scene investigation was essential
• Manner of death - accident

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Chemical and lack of available oxygenin the
atmosphere

• O2 is replaced by another chemical or gas
• Closed environment
• mine shafts, sewers, or chemical storage tanks
• Red blood cells are unable to deliver oxygen to
  bodily tissues
• Carbon monoxide
• Competes with O2
• Cyanide
• smells like bitter almonds
• can occur quickly, especially cyanide poisoning

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Drowning

• The diagnosis of drowning - exclusion
• Diatoms
• The autopsy is usually negative
• Diagnosis
• Body is wet, or is found in water.
• There may be injuries from being in the water
• Tears and scrapes skin from impacts against boats
  or bridges
• Feeding by marine life - skin of the face,
  especially around the mouth, nose, and ears
• Abrasions may be found on the forehead, knees,
  and backs of hands from scraping
• No external signs of trauma
• Froth in the nose and mouth
• Wrinkling of the skin on the hands and feet
• Injuries to the body may occur from CPR attempts
  or from removing the body from the water.
• Heavy, wet lungs in those individuals who drown
  in salt water,