Transcript 11 Electro - bloodhounds Incorporated

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
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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