Detective Jeff Maag told the entertainment industry trade newspaper Wednesday more work needs to be done before the cause of the wreck is officially determined.
Although some media reports have claimed the Porsche was going at least 90 mph at the time of the collision, Maag said that is speculation and all he is comfortable saying is the car was traveling at least 45 mph when it hit a tree and light pole the afternoon of Nov. 30 in Santa Clarita, Calif.
Walker was a passenger in the car, which was driven by his friend, Roger Rodas, who was also killed.
"We're creating a factual diagram -- mapping the scene," he told THR. "To the extent that we can, we need to rule out mechanical failure. But the car is a mess."
The newspaper also said a makeshift memorial had been created by fans at the accident scene and investigators tried to leave it intact for as long as possible out of respect for the mourners
It was removed Tuesday.
Walker's remains were released to a mortuary Monday after the Los Angeles County Coroner's Office completed an autopsy and determined he died of traumatic and thermal injuries as a passenger in the fiery crash. He was 40.
Toxicology test results are not expected to be released for about seven weeks, THR said.