Forensic Pathology

Blunt Trauma Types

• Contusions

– Black and Blue marks

• Abrasions

– Scrapes

• Lacerations

– Split versus cut

CUTTING AND STABBING

• 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

1. Soot or fouling

• Completely burned gunpowder

• can be washed off the skin

2. tattooing” or “stippling.”

• Particles of burning and unburned powder

• Become embedded or abrade in the skin

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 GasesReddening Due to CO

Muzzle Blow-back

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

• 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

Two Exit Wounds with Hemorrhage

On the left – Entrance WoundOn the right – Exit Wound

Note beveling

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 yardThree 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 causedExtreme 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 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

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,