FORENSIC PATHOLOGY

ELECTROCUTION

ELECTROCUTION

• Virtually all accidents– Alternating currents

• Most common type found in homes in the US– Low (<600 V)– High (>600-750 V)

• Amperage is most important factor in the current flow

A = V/R

ELECTROCUTION

• Voltage– Household – 110V

• Must directly touch electrical circuit• Death mainly by ventricular fibrillation

– High voltage lines – 8000 V• Electric current may jump (arc)• Death mainly by electrothermal injury or

respiratory arrest

ELECTROCUTION

• Resistance– Mainly by skin

• Dry skin has resistance of 100,000 ohms

• Dry calloused skin has resistance of 1,000,000 ohms

• Moist skin has resistance of 1,000 ohms

• Wet skin has resistance of 100 ohms

• Mechanism of Death– Minimal perceptible amperage

= 1mA– 5 mA will produce tremors in

muscle– 15 mA causes contractions– 50 mA causes respiratory

paralysis and death– 75 mA causes ventricular

vibrillation– 1 A causes ventricular arrest

ELECTROCUTION

• Judicial execution– High voltage currents

• Produces– 3rd degree burns– Brain temperature up

to 63°C

ELECTROCUTION

• Electroconvulsive “shock” Therapy– May cause fracture of

bones• Due to muscle

contractures• Most common are T12

and L1 vertebrae along with scapular fractures bilaterally

ELECTROCUTION

• Muscle Contraction– Back and neck arch backward– Arms rotate inward, elbows flex and hands

form fists– Hips and knees lock straight and feet extend– Individuals may grasp and continue to do so

ELECTROCUTION

• Autopsy Findings– High Voltage

• Electrical burns over body– Low Voltage

• Electrical burns at point of entry or exit• May have no electrical burns if minimal resistance

to flow– Bathtub

• Muscle Contraction

ELECTROCUTION

• Low Voltage Burns– Most often on palms of hands and tips of

fingers– Erythematous or blistering– Chalky white lesions– Raised borders with central crater– Yellow or black discoloration at burn site

ELECTROCUTION

• A typical electrical burn consists of a round, oval or elongated crater.

• Base of wound is dark brown.

• Ridge of elevated skin on margin

ELECTROCUTION

ELECTROCUTION• If victim survives for

short period of time after contact there may be a collection of foam in air passages.

ELECTROCUTION

• High Voltage Burns– Charring of body– Current runs through intermediary object

• Burns are large and irregular• Chalky white• Raised borders and central crater• Yellow black discoloration at burn site• Massive tissue destruction• Organ rupture

ELECTROCUTION

• Manner of Death– Usually all accidental– May be sexual in nature– Suicides and homicides are rare

• Ground-Fault Current Interrupters (GFCI)– Circuit is broken if amperage increases by 5 mA

ELECTROCUTION

• Lightning– Charged undersurface of a thunder cloud

• Virtually always Negative• Electrical charge to the ground

– Direct Strike• May injure or kill person

– Side flash• Hits an object and ricochets

ELECTROCUTION• Side-Flash Strike

– Clothing torn, shoes burst, hair seared, burned on skin from zipper or other metal objects

– Entrance and exit burns– Rupture of tympanic

membrane– Death by cardiopulmonary

arrest or thermal injury• Injury to cardiac and respiratory

centers of brain

ELECTROCUTION

• Aborescent Lightning injury– Fern-like pattern– Lichtenberg figures– Appears within 1h of lightning injury and fades within

24h– Not burns

• May be due to a positively charged lightning bolt• May be due to flashover by positive discharge over skin• Really don’t know what causes this pattern