LOS ANGELES (Reuters) -- The fiery car accident last year that killed Fast & Furious actor Paul Walker was caused by excessive speed and not mechanical failure, the Los Angeles County Sheriff said Tuesday, concluding an almost four-month investigation.
The red Porsche Carrera GT sports car driven by Walker's friend Roger Rodas, 38, was traveling at speeds of 80 to 93 mph before Rodas lost control of the car and crashed into trees and a utility pole in Santa Clarita, Calif.
"Investigators determined the cause of the fatal solo-vehicle collision was unsafe speed for the roadway conditions," Los Angeles County Sheriff Commander Mike Parker said in a statement.
Parker said the 2005 high-powered sports car had been modified to increase its horsepower. There were no pre-existing issues with the car that would have caused the crash, the investigation concluded.
The posted speed limit on the road where the accident occurred is 45 mph. There were no eyewitnesses to the crash and investigators from the sheriff's department and California Highway Patrol used security video cameras in the area to gather evidence.
Walker, 40, died from traumatic injuries and burns and Rodas died of multiple traumatic injuries in the Nov. 30 crash, the Los Angeles County coroner's office determined in January.
No drugs or alcohol were found in the bodies of Walker and Rodas. The investigation determined that they were wearing seatbelts, and driver and passenger airbags had deployed.
Investigators also sought help with the inquiry from German carmaker Porsche and French tire manufacturer Michelin.
Walker was filming Fast & Furious 7 at the time and production was halted a few days later.
The actor became a symbol of street racing and car culture in his role as law enforcement officer Brian O'Conner in five of the six Fast & Furious films about illegal street racing, heists and organized crime.
Universal Pictures said in December that release of the seventh installment in the highly lucrative franchise would be pushed back by nine months to April 2015.