Forensic Pathology

Blunt Trauma Types Contusions Abrasions Lacerations Black and Blue marks Abrasions Scrapes Lacerations Split versus cut

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

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.

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

Single-edged Knife Light arrow = blunt angle Dark arrow = sharp

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, wrists, or leg area Varying depths on the wound suggest a suicide. Hesitation marks are characteristic Overkill A body sustaining tens or hundreds of stab and incised wounds Highly emotional setting Sex Drugs

What Do These Wounds Indicate?

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

Some Wounds Can be Caused by Treatment Lower two wounds were caused by thoracotomy incisions to drain blood from the chest

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

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. Blow to the head → bleeding under the scalp May be skull fractures ID weapon or type of instrument

Battle’s sign Bluish discoloration of the skin behind the ear Blood leaking under the scalp after a skull fracture

Spectacle hemorrhage Discoloration of the tissues around one or both eyes Caused by a fracture of the skull Can be mistaken for blows to the face and eyes

Fell Down the Stairs multiple areas of subscalpular hemorrhage Series of blows to the head

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

Cerebral Contusion Focal brain injury is an injury to: 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.

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

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

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.

Firearms – Hand Guns and Rifles Primer – stable, but shock sensitive Gunpowder or propellant – volumes of gas Bullet or projectile

Gunpowder Soot or fouling tattooing” or “stippling.” 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

What was the Range – Tight Contact Reddening Due to CO Muzzle Blow-back Splitting Due to Gases 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.

Loose contact Gunpowder deposited around the edges of a wound

Close range muzzle-to-target distances of approximately 6–12” Both fouling and stippling are present Abundant Soot After washing - Stipling Powder and Fouling

Distant wounds — No fouling or stippling. 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.

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.

Entrance and Exit Wounds 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 Slit-like Ragged edges No Rim of abrasion unless victim is against another object shored Skin around discolored because of underlying bleeding in the soft tissues. May be circular like entrance wounds

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

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

Shotgun Wounds Shot by police from across a yard Three pellets entered the heart

ASPHYXIA 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

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 Unconscious in seconds Pressure must be continued in order to cause death.

Signs of Trauma to the Neck Contusions or abrasions, rarely lacerations Abraded, imprinted mark Thin ligature – pattern 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,

Ligature Marks

Petechiae (pet-TEA-key-eye) Pinpoint hemorrhages 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 Lower extremities

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 infant’s or child’s 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

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

Postural or Positional Asphyxia Compression of the chest, neck, or face person cannot breathe because of an inability to move one’s 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

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

Chemical and lack of available oxygen in 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

Drowning The diagnosis of drowning - exclusion Diagnosis 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,