FORENSIC PATHOLOGY
Motor Vehicle Accidents
MOTOR VEHICLE ACCIDENTS
Why perform an autopsy after a MVA?
Determine cause of death
Confirm death was caused by injury in the MVA
Determine extent of injuries
Detect any disease or factor which may contribute
to MVA
Document findings for criminal or civil case
Establish positive ID of body
MOTOR VEHICLE ACCIDENTS
Causes of MVA
Impairment of driver is most common
• 50% of all crashes are due to DUI of alcohol or
drugs
– Drugs may be prescription
– Even marijuana impairs driving skills
2nd cause is human error
• Speed, reckless driving, falling asleep at wheel
3rd cause is environmental hazards
MOTOR VEHICLE ACCIDENTS
Four Major Categories of MVA’s in
descending order of fatality for
automobiles
Front impact
Side impact
Rollovers
Rear impact
MOTOR VEHICLE ACCIDENTS
Four major categories of MVA’s for
pickups and utility vehicles in
descending order of fatalities
Rollovers
Frontal impact
Side impact
Rear impact
MOTOR VEHICLE ACCIDENTS
Front Impact Crashes
In a head on collision if the driver is not
restrained the body will continue its frontal
movement
• Strike instrument panel at knees
• Strike chest on steering wheel
• Strike head on windshield of visor
MOTOR VEHICLE ACCIDENTS
Front Impact Crashes
Knees
• May have patterned abrasions
• Fractures of the patella
• Fractures of the femur or hip joint
– Especially neck of femur
– Exsanguination may occur
MOTOR VEHICLE ACCIDENTS
Front Impact Crashes
Chest
• May impact steering wheel or dashboard
• Imprinted abrasions/contusions
• Internal injuries
– Fracture of sternum and/or ribs
– Lacerations, contusions, rupture, transection of vital
organs
– Liver, spleen, heart, aorta
MOTOR VEHICLE ACCIDENTS
Front Impact Crashes
Head
• Patterned abrasions
• Impact windshield
– Windshield does not shatter
– Thin outer and inner layers of glass, thick core of
plastic
– Dicing injuries
• Avulsion of skin especially to head
• Basilar fractures of skull
– Hinge fractures
• Fractures of neck
• Atlanto-occipital junction dislocation
MOTOR VEHICLE ACCIDENTS
MOTOR VEHICLE ACCIDENTS
Unrestrained injuries usually occur in
sequence
Knee-femur-hip-chest-head
Restrained injuries are dependent on
the force of the crash
MOTOR VEHICLE ACCIDENTS
MOTOR VEHICLE ACCIDENTS
Side Impact Crashes
Broadside at intersections most common
Driver’s side
• Head can flex laterally through side window
• Head may hit pillar of car
• Injuries are typically worse on left side of body
• Head may pop out of window and pop back
into vehicle
– Head may hit objects before re-entering vehicle
MOTOR VEHICLE ACCIDENTS
Rollovers
Generally less lethal than head-on and side
impact collisions
If not wearing seatbelt may be thrown
around like a rag doll in compartment
• Receive multiple injuries
• Body may also pop out of vehicle and pop back
in again
– Check for paint on head or hair on vehicle
MOTOR VEHICLE ACCIDENTS
Rollovers
Most rollovers occur because driver runs off the
road and attempts to steer back onto road
Vehicle skids sideways
Vehicle tips towards leading side
Where rollover begins is where tire marks stop
Center of gravity determines extent of rollover
• SUV’s rollover more
MOTOR VEHICLE ACCIDENTS
Rollovers
Vehicles that roll over go airborne
Cars land on edge of roof opposite side
that led in rollover
SUV’s impact on leading edge of vehicle
roof then onto tires
Most vehicles only roll over once
MOTOR VEHICLE ACCIDENTS
Rear Impact Crashes
Least common of fatal accidents
Mainly see whiplash syndrome
May have fire due to faulty gas tank
May have seatback failure
MOTOR VEHICLE ACCIDENTS
MOTOR VEHICLE ACCIDENTS
Seat belts
Lap belts
Shoulder belts
Three-point belts
• Lap plus shoulder
MOTOR VEHICLE ACCIDENTS
Seat belts
All new vehicles have three-point belts
Since 1997, 69% decrease in MVA
fatalities due to seat belt law
Jack-knifing may occur with lap belts
Seat belt syndrome
MOTOR VEHICLE ACCIDENTS
Air bags
Significantly less effective than seat belts
• Only improves your chance of survival by a
maximum of 5%
• May produce injuries especially in children and
small adults
– Less than 10 inches from bag
MOTOR VEHICLE ACCIDENTS
Motorcycle Accidents
Fatalities are due mostly to head or neck
injuries
Many abrasions
High speed crashes wearing helmets are
only to keep brain matter from spreading
over the freeway
MOTOR VEHICLE ACCIDENTS
Motorcycles
Most fatalities are due to
• Car drivers don’t see the motorcycle
• Environmental factors
• Wires or cables stretched across roadway
– Avulsed limbs
– Decapitation
MOTOR VEHICLE ACCIDENTS
Suicide by Motor Vehicle
Usually head on into a fixed object
Check soles of shoes of driver for pedal
marks
• May also do this to determine who was driving
in a crash
MOTOR VEHICLE ACCIDENTS
Toxicology and MVA’s
A complete toxicological screen should be done
• Include Carbon Monoxide levels
In 1999, 38% of traffic fatalities were alcohol
related down from 49% in 1989
Should also drug test passenger
• Passenger often turns out to be driver
• Blood may be kept at a hospital for up to 7 days
MOTOR VEHICLE ACCIDENTS
Pedestrian Deaths by MVA’s due to four
factors
Speed of vehicle
Physical characteristics
Braking of vehicle
Whether victim was a child or an adult
MOTOR VEHICLE ACCIDENTS
Pedestrian Death – Speed of Vehicle
Fracture of spine, 45 km/h
Rupture of thoracic aorta, 85 km/h
Inguinal skin rupture, 95 km/h
Dismemberment, above 95 km/h
MOTOR VEHICLE ACCIDENTS
SUV’s
Child Pedestrians
• Body’s center of gravity is below bumper
– For non-braking or late braking vehicle: Victim will
be impacted, slammed down and run over
– For braking vehicle: Front of vehicle dips below
child’s center of gravity and child may be thrown
forward
MOTOR VEHICLE ACCIDENTS
Adult Pedestrians
Body’s center of gravity is above bumper,
except for tall vehicles, i.e. pick-up or SUV
• Trucks or SUV’s
– Non-braking: Victim is slammed down and run-over
– Braking: Victim is thrown forward
MOTOR VEHICLE ACCIDENTS
Adult Pedestrians
Automobiles or light trucks
• Non-braking or late braking at high speeds: Victim is
picked up and thrown over top of car
– Look for scuff marks or dents on bumper, hood, roof
and possible trunk of vehicle
• Non-braking at moderate speeds: Victim will be picked
up, land on the hood and slide backward impacting
windshield, then slide off (usually sideways)
– Look for scuff marks or dents on bumper, indent on
hood and impact to windshield
– Glass may be in hair of victim
– May find hair or clothing in cracks in paint or in glass
on vehicle
MOTOR VEHICLE ACCIDENTS
Automobile or Light trucks
Braking at high speeds: Victim may be
thrown forward or may be picked up and
land on the hood and then propelled
forward again
• Look at knees and calf region for fractures
– “Bumper Fractures”
– If walking or standing sideways may be fractures at
different levels or fracture in only one leg
MOTOR VEHICLE ACCIDENTS
Automobile or light truck
Individuals picked up and thrown by a
vehicle may be stripped of clothing
If Victim is run over by a wheel
• Look for tire marks and abrasions on opposite
side of body
MOTOR VEHICLE ACCIDENTS
Future of MVA’s
Black Boxes
• Already in Mercedes and
• All GMAC models
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