Autopsy & forensics
Types of injuries
Motor vehicle deaths
Author: Lindsey Harle, M.D.
Last author update: 1 August 2012
Last staff update: 26 August 2019
Copyright: (c) 2012-2019, PathologyOutlines.com, Inc.
PubMed search: "Motor vehicle" death forensic
Cite this page: Harle L. Motor vehicle deaths. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/forensicsmotorvehicledeaths.html. Accessed March 22nd, 2023.
Types of collisions
Frontal impact:
- Most common (80%); occurs when two vehicles collide head on, or when a single vehicle hits a stationary object head on
- Vehicle occupants continue moving forward due to kinetic energy; impacting the windshield and dashboard
- Drivers show trauma of the anterior head due to impact with windshield or visor; may show skull fractures, atlantooccipital dislocation, neck fractures, diffuse axonal injury
- Drivers may have chest injuries due to impact with the steering wheel, with sternal and rib fractures, pulmonary contusions and lacerations (due to rib fractures), cardiac laceration / contusion, aortic dissection, hepatic and splenic lacerations
- May show pattern impact injury of the steering wheel
- Drivers may show wrist or forearm fractures if hands were positioned on wheel at time of impact
- Drivers may have patellar or femoral fractures due to impact with dashboard; or ankle fractures
- "Dicing injuries" to the left face and left arm: small abrasions / lacerations on driver due to shattering of the driver side window
- Front seat passengers: injuries similar to driver, but no steering wheel impact
- Dicing injuries of the right face and right arm due to shattering of passenger side window
- Unrestrained rear passengers may be thrown to front compartment of vehicle
Side impact:
- Usually due to one vehicle impacting the side of another vehicle
- All injuries seen in frontal impact collisions can occur
- Injuries should be more severe on side of impact; individuals on impacted side should have more severe injuries than those on the opposite side
Rear impact:
- May cause "acceleration" injuries (e.g. whiplash) which tend to be less severe
Rollover:
- Tend to be more severe; many different injury patterns can occur
- May cause traumatic asphyxia if individual is ejected and becomes trapped beneath vehicle
- May see pattern injury from seatbelts; pattern should correspond to position of individual in car (e.g. driver vs. passenger)
- Seatbelts can produce mesenteric, omental, or bowel contusions / lacerations
Suicidal motor vehicle accidents
- Vehicle directly collides with fixed object or another vehicle
- No signs of braking at scene
- Decedent may have history of suicidal ideation or suicide attempts
Pedestrian deaths
Factors influencing injury pattern:
- Vehicle speed: high speed impact may cause pedestrian to be thrown over vehicle
- Braking may result in pedestrian being "picked up" by vehicle or being thrown forward
- Type of vehicle: larger vehicles that hit pedestrian above their center of gravity tend to knock them down rather than pick them up
- Size / age of pedestrian: impact below pedestrian’s center of gravity causes them to be lifted and thrown
Injuries sustained by pedestrians:
- Tire / tread marks: on skin or clothing; can link pedestrian to vehicle
- Pattern injuries: in addition to tire marks, can include impressions of bumper, headlights, or other parts of vehicle; can be used to link pedestrian to vehicle
- Bumper fractures: occur when bumper strikes pedestrian's lower extremities; may not be associated with overlying cutaneous injury
- Measure distance from heel to estimate bumper height
- Contusion pockets: collections of blood in subcutaneous tissue or muscle; due to impact with hood or bumper
- "Stretch" lacerations of inguinal folds: due to overstretching of body at hip joint; appear yellow and dry
- Suicidal pedestrian deaths: need witness information and decedent history of suicidal ideation to corroborate
Motorcycle deaths
Types of injury:
- Head trauma: most common lethal injury; may occur even in individuals wearing a helmet
- Basilar skull fracture is most common
- Motorcycle passengers tend to fall backwards, producing lacerations and fractures of posterior head
- Brush abrasions ("road rash") on exposed skin
- Traumatic asphyxia: may occur if motorcycle lands on individual
Bicycle deaths
- Most bicycle accidents produce only minor trauma
- Degree of injury is largely related to speed of the impact
- Bicycle spoke injury: occurs when leg or foot passes through wheel spokes; causes crushing / avulsion of soft tissues; more common in children
Evidence to examine
- Toxicology of driver, passenger, and pedestrian, to include carbon monoxide for vehicle occupants
- Trace evidence: hair, blood, clothing fibers, glass chips, or paint chips can be used to link a car to a pedestrian death, or to determine a person's position in vehicle
