Death of Joshua Brown, the former Navy SEAL who was killed when his Tesla drove rammed into a tractor, has raised questions over the efficacy of autonomous technologies.

Brown, 40, was killed in Florida May 7 when his Tesla S came under a trailer and had its roof torn off from impact. Brown was in the driver's seat and the car on autopilot. New reports suggest the car was speeding and its cameras failed to distinguish the trailer ahead from its environment.

The trailer's driver, Frank Baressi, told authorities that Brown was watching Harry Potter when the crash happened. He said he heard the movie play, which continued even after the crash. Baressi also said that Brown was driving fast and he did not see the Tesla coming.

A proud Tesla owner, Brown espoused the company's Autopilot software and trusted it with his life. He even uploaded videos to YouTube showing how the feature had saved his Tesla from an accident. Those who knew him said he drove the car across the country and was so attached to it he named it 'Tessy'. One of his videos was reportedly picked up by Tesla CEO Elon Musk for the automaker's website.

News of the accident broke a few days ago, raising questions why investigating federal authorities and Tesla kept mum about the accident for nearly two months after what is now recognized as the first fatality during autonomous drive. The New York Times also pointed out that Musk did not mention the accident to shareholders end of May during a meeting. However, the company has stated its Autopilot is beta and that it is to be used with driver oversight.

Though Teslas across the world have reportedly done around 130 million miles on Autopilot without fatalities, the accident has raised concerns about the technology, with analysts calling for Musk to ensure the technology is tested before making it commercially available. Details from the incident, including witnesses who claimed the car continued to speed after its roof was ripped off, are fuelling concerns.