US company Tesla, which sells electric cars, is being investigated following a road crash involving one of its vehicles and a lorry in Florida in which a man died.
Under scrutiny is the electric car company's autopilot feature, a function which automatically changes lanes and reacts to traffic.
Tesla said it appeared the car's system was unable to recognise "the white side of the tractor trailer against a brightly lit sky" that had driven across the car's path.
Tesla stressed that cars being controlled by autopilot had travelled 130 million safe miles to date.
Police and a lawyer for the lorry driver said a DVD player had been found in the car, with a 'Harry Potter' DVD inside.
A police spokeswoman said there was no camera found, mounted on the dash or of any kind, in the wreckage.
Paul Weekly, the lawyer for the lorry truck driver, said: "As to the video, there was a witness who came to the scene immediately after the accident occurred, and we can't verify it at this point.
"But what we have been told is that he saw a Harry Potter video still playing when he got to the scene. Again, I can't verify that."
The lorry driver, 62-year-old Frank Baressi said the implact of the Tesla Model S "lifted the trailer up and jolted the heck out of it when he went under it. It sheared the top of the car right off".
The accident, which according to a report from the Florida Highway Patrol killed a 40-year-old man on a clear, dry roadway on 7 May in Williston, Florida, will add fuel to a debate within the auto industry and in legal circles over the safety of systems that take partial control of steering and braking from drivers.
Mr Weekley said the centre console of the car was not seriously damaged, meaning that the electronic data recorder, the so-called "black box" for the car, should have been intact.
The recorder had been removed from the Model S before his investigators were able to see it, he said.
