FORENSIC PATHOLOGY ELECTROCUTION ELECTROCUTION Virtually all accidents Alternating

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 – 110 V • 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 ohms • Moist skin has resistance of 1, 000 ohms • Wet skin has resistance of 100 ohms

• Mechanism of Death – Minimal perceptible amperage = 1 m. A – 5 m. A will produce tremors in muscle – 15 m. A causes contractions – 50 m. A causes respiratory paralysis and death – 75 m. A causes ventricular vibrillation – 1 A causes ventricular arrest

ELECTROCUTION • Judicial execution – High voltage currents • Produces – 3 rd degree burns – Brain temperature up to 63°C

ELECTROCUTION • Electroconvulsive “shock” Therapy – May cause fracture of bones • Due to muscle contractures • Most common are T 12 and L 1 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 m. A

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 1 h of lightning injury and fades within 24 h – 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