The mysterious death of an Australian film student on a Hollywood freeway continues to baffle US authorities.

Rishi Chaubal-Menon, 18, a former student of Melbourne’s elite Scotch College, was found dead on the Hollywood Freeway shortly after midnight on October 31.

California Highway Patrol investigators believe the teenager may have been the victim of a hit-and-run driver.

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However, they did not find broken glass or pieces of a car usually associated with a crash at the scene.

“We have exhausted all of the leads we have,” Captain Johnny Starling, of the California Highway Patrol, told reporters at a Los Angeles press conference in the hope of generating new leads.

Mr Chaubal-Menon had just begun studies at the New York Film School’s Los Angeles campus.

Investigators do not know why he was walking on the busy freeway.

The film school has put up a $US10,000 ($A13,580) reward for information leading to an arrest of a hit-and-run driver.

Mr Chaubal-Menon’s death has devastated his close-knit family and students at the film school.

He had been in Los Angeles for less than a month and excitedly wrote on his Facebook page about the excitement of embarking on a film career.

“Tomorrow I finally start the next chapter of my life,” he wrote on October 2.

“Undeniably, the road has had its bumps, but I have a clear path in mind with a goal that may seem laughable to many. I believe it is this attitude that sets people back.”