Authorities say they've arrested an 18-year-old accused of stealing part of the Porsche that Fast & Furious star Paul Walker was in when he was killed in a crash.

The Los Angeles County Sheriff's Department says Jameson Witty was arrested at his LA-area home. A statement from the agency Thursday says another suspect who is 25 years old is outside California and arranging to surrender.

The Sheriff's Department says the wreckage of the 2005 Porsche Carrera GT was being towed away after Saturday's fatal crash when someone got out of a car following the tow truck, grabbed a part and drove away.

Detectives say they found the Porsche's roof panel while searching a home in Canyon Country, a community north of Los Angeles.

It wasn't clear if Witty has an attorney, and no phone listings for family could be found.

Crash still under investigation

Walker was killed by injuries from both the impact and subsequent fire when the high-powered Porsche driven by his friend Roger Rodas crashed, according to autopsy results released Wednesday.

Investigators are still probing what exactly caused Rodas to lose control, but have said speed was a factor.

According to witnesses, Walker and Rodas had been attending an event for the actor's charitable organization Reach Out Worldwide when they decided to take the car for a brief test drive.

Detectives continue to gather evidence and investigate the cause of the crash, including poring over surveillance video from the area. The remains of the Porsche have been moved to a Sheriff's department impound yard. Fans continue to flock to the site daily to mourn the star, according to police officials.

Meanwhile, Universal Pictures has shut down production on Fast & Furious 7 indefinitely following the death of Walker.

The studio announced Wednesday that the film will shut down "for a period of time so we can assess all options available to move forward with the franchise."

The seventh installment of the street car racing series had begun shooting in September. While much of Fast & Furious 7 has been filmed, it's far from complete.