After Fatal Autopilot Crash, Laptop, DVD Player Found in Tesla

— -- A laptop and laptop mount were found in the Tesla that crashed and killed its sole occupant while driving down a Florida highway on autopilot in May, the state highway patrol told ABC News. A portable DVD player was also found in the vehicle, the department previously told ABC News.

Because the impact was so severe, authorities say they may never know whether the driver, 40-year-old Joshua Brown, was using either device at the time of the crash. But a witness told the driver of another vehicle involved in the accident he noticed a Harry Potter movie playing in the Tesla as he ran past it, according to the driver’s attorney.

Brown, a former Navy explosive ordinance disposal technician, was a long-time Tesla enthusiast who had lauded its autopilot system in videos posted online.

“What do you do with your hands while you’re driving while on auto-steer? It’s a good question, because they tell ya, always have your hands on the wheel,” Brown said in one YouTube video.

“How I actually do it is so that it is really actually hands free, is, I keep my knees up," he said. "You can react so quickly so that if anything goes wrong, you can very quickly take control without really anything having happened.”

Tesla calls autopilot an “assist feature” and says it expects drivers to keep their hands on the wheel, “prepared to take over at any time.” Activating autopilot, which is disabled by default, prompts an on-screen reminder.

According to the automaker –- which mourned Brown’s death, calling it a “tragic loss” –- this is the first known fatality in over 130 million miles of autopilot driving. (In comparison, the U.S. average is one fatality per 94 million miles driven.)

According to the National Highway Traffic Safety Administration (NHTSA), a tractor-trailer made a left turn in front of the Tesla Model S at an intersection. Tesla says, “neither Autopilot, nor the driver noticed the white side of the tractor-trailer against a brightly lit sky, so the brake was not applied.” The Tesla then careened underneath the trailer, shattering its windshield and fatally injuring Brown.

"This accident was the result of a semi tractor-trailer crossing both lanes of a divided highway in front of an oncoming car. Whether driven under manual or assisted mode, this presented a challenging and unexpected emergency braking scenario for the driver to respond to," Tesla CEO Elon Musk said in a statement, railing against scrutiny over Tesla's disclosure of the incident.

"In the moments leading up to the collision, there is no evidence to suggest that Autopilot was not operating as designed and as described to users: specifically, as a driver assistance system that maintains a vehicle's position in lane and adjusts the vehicle's speed to match surrounding traffic," he added.

Prior to the crash, Musk told Bloomberg, “We're going to be quite clear with customers that the responsibility remains with the driver,” adding, “we’re not asserting that the car is capable of driving in the absence of driver oversight.”

NHTSA has opened a preliminary investigation into the automated system.

“The Brown family is committed to cooperating in these efforts and hopes that information learned from this tragedy will trigger further innovation which enhances the safety of everyone on the roadways,” the driver's family told ABC affiliate WEWS-TV in Cleveland, Ohio.

ABC News' Becky Perlow contributed to this report.