LOS ANGELES -- 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 on 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 29 to 150 kilometers per hour before Rodas lost control of the car and crashed into trees and a utility pole in Santa Clarita, California, northwest of Los Angeles.
"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 model-year 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 72 kph. 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 in the process of 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.
At a convention of movie theater owners in Las Vegas on Tuesday, Universal showed a clip of the film featuring some of Walker's final scenes.
Walker's 15-year-old daughter, Meadow, is the sole beneficiary of his estate, which is valued at more than $16 million, according to court documents.
The actor's mother is petitioning a Los Angeles court for guardianship of Meadow.