The body of The Fast and the Furious star Paul Walker underwent an autopsy early Tuesday, along with friend and business partner, Roger Rodas, both of whom died in a car crash on Saturday that caused the car to catch fire, burning both men inside to the point that their bodies were indistinguishable. Because of this, the Los Angeles County coroner will not release results until a later date.

“We’re waiting for dental records,” said Edward Winter, spokesman for the coroner, according to the Chicago Tribune. “The bodies are unidentifiable.” In addition to matching the bodies with dental records, the coroner will do X-rays in order to find out whether “the damage actually matches the preliminary findings,” Winter told the Daily News.

The dental records are necessary because both men’s teeth might be the only way to identify them accurately. Teeth can survive heat up to 1,200 degrees Fahrenheit, Dr. Roy Sonkin, deputy borough chief forensic odontologist at the Office of the Chief Medical Examiner in New York City, told ABC News. “The dentist methodically and meticulously goes over everything, tooth by tooth, comparing each crown, cavity, implant, and ‘virgin’ tooth that has been untouched by a dentist,” he told ABC. “We often ask the family for photographs of the person smiling for further confirmation.”

Along with identifying which body belongs to whom, the coroner is also looking to see how exactly Walker and Rodas died. Specifically, if they died from blunt force trauma, smoke inhalation, or thermal burns. “We probably can do toxicology tests as well. That would be part of the full autopsy,” Winter told the Daily News.

Both men, who were part of the same racing team, Always Evolving, were seen getting into the red 2005 Porsche Carrera GT minutes before the car hit a tree and pole, and burst into flames. Authorities had determined that the crash was not the end result of a street race with another car, but said that speed was a factor. What’s more, Rodas, who had taken ownership of the vehicle over the summer, hadn’t yet tested the vehicles true speed on a racetrack, the Daily News reported.

“If I had a guess, I’d say (Roger) put his foot into it just to feel the power a little bit, and the car did something unnatural,” a source told the Daily News. “It was a nervous, twitchy car, and I really believe Roger’s last thought was: ‘What just happened?’”