Joan Lowy and Tom Krisher

Associated Press

WASHINGTON — A driver was so enamored of his Tesla Model S sedan that he nicknamed the car “Tessy,” praised the safety benefits of its Autopilot system and was watching a Harry Potter video when he became the first person to die in a wreck involving a car in self-driving mode.

The National Highway Traffic Safety Administration announced the driver’s death Thursday and said it is investigating the design and performance of the Autopilot system.

Joshua D. Brown of Canton, Ohio, the 40-year-old owner of a technology company, was killed May 7 in Williston, Fla., when his car’s cameras failed to distinguish the white side of a turning tractor-trailer from a brightly lit sky and didn’t automatically activate its brakes, according to statements by the government and the automaker. Just one month earlier, Brown had credited the Autopilot system for preventing a collision on an interstate.

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Frank Baressi, 62, the driver of the truck and owner of Okemah Express, said the Tesla driver was “playing Harry Potter on the TV screen” at the time of the crash and driving so quickly that “he went so fast through my trailer I didn’t see him.”

The movie “was still playing when he died,” Baressi told the Associated Press in an interview from his home in Palm Harbor, Fla., saying the careening car “snapped a telephone pole a quarter-mile down the road.” He acknowledged he didn’t see the movie, only heard it.

Tesla Motors said it is not possible to watch videos on the Model S touch screen. There was no reference to the movie in initial police reports.

Brown's driving record, obtained by the Associated Press, showed he had eight speeding tickets in a six-year span. Seven came in Ohio and one in Virginia. The most recent ticket, in northeastern Ohio in August 2011, was for driving 64 m.p.h. in a 35 m.p.h. zone.

Brown’s published obituary described him as a member of the Navy SEALs for 11 years and founder of Nexu Innovations, working on wireless Internet networks and camera systems. In Washington, the Pentagon confirmed Brown’s work with the SEALs and said he left the service in 2008.

Brown was an enthusiastic booster of his 2015 Tesla Model S and in April praised the Autopilot system for avoiding a crash when a commercial truck swerved into his lane on an interstate. He published a video of the incident online. “Hands down the best car I have ever owned and use it to its full extent,” Brown wrote.

In a statement released Friday, Brown’s family noted his “passion for technological advancement” and said they are cooperating with the investigation. The family hopes “information learned from this tragedy will trigger further innovation which enhances the safety of everyone on the roadways.”

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Tesla didn’t identify Brown but described him in a statement as “a friend to Tesla and the broader EV (electric vehicle) community, a person who spent his life focused on innovation and the promise of technology and who believed strongly in Tesla’s mission.” It stressed the uncertainty about its new system, saying drivers must manually enable it: “Autopilot is getting better all the time, but it is not perfect and still requires the driver to remain alert.”

A man answering the door at Brown’s parents’ house who did not identify himself said he had no comment.

Tesla founder Elon Musk expressed condolences in a tweet late Thursday.

Preliminary reports indicated the crash occurred when Baressi’s rig turned left in front of Brown’s Tesla at an intersection of a divided highway southwest of Gainesville, Fla., where there was no traffic light, NHTSA said. Brown died at the scene.

By the time firefighters arrived, the wreckage of the Tesla — with its roof sheared off completely — had come to rest in a yard hundreds of feet from the crash site, assistant chief Danny Wallace of the Williston Fire Department told the AP.

Tesla said in a statement that this was the first known death in more than 130 million miles of Autopilot operation. Before Autopilot can be used, drivers have to acknowledge that the system is an “assist feature” that requires a driver to keep both hands on the wheel at all times. Drivers are told they need to “maintain control and responsibility for your vehicle” while using the system, and they have to be prepared to take over at any time, the statement said.

Autopilot makes frequent checks, making sure the driver’s hands are on the wheel, and it gives visual and audible alerts if hands aren’t detected, and it gradually slows the car until a driver responds, the statement said.

The Autopilot mode allows the Model S sedan and Model X SUV to steer itself within a lane, change lanes and speed up or slow down based on surrounding traffic or the driver’s set speed. It can automatically apply brakes and slow the vehicle. It can scan for parking spaces and parallel park on command.

NHTSA said the opening of the preliminary evaluation by its defects investigation office shouldn’t be construed as a finding that the government believes the Model S is defective.

Brown’s death comes as NHTSA is taking steps to ease the way onto the nation’s roads for self-driving cars, an anticipated sea-change in driving. Self-driving cars have been expected to be a boon to safety because they’ll eliminate human errors. Human error is responsible for about 94% of crashes.

One of Tesla’s advantages over competitors is that its thousands of cars feed real-world performance information back to the company, which can then fine-tune the software that runs Autopilot.

This is not the first time automatic braking systems have malfunctioned, and several have been recalled to fix problems. Last fall, Ford recalled 37,000 F-150 pickups because they braked with nothing in the way. The company said the radar could become confused when passing a large, reflective truck.

The technology relies on multiple cameras, radar, laser and computers to sense objects and determine if they are in the car’s way, said Mike Harley, an analyst at Kelley Blue Book. Systems like Tesla’s, which rely heavily on cameras, “aren’t sophisticated enough to overcome blindness from bright or low contrast light,” he said.

Harley called the death unfortunate, but said that more deaths can be expected as the autonomous technology is refined.