PERTH, Australia, Feb 5, 2008 (AFP) - The family of Hollywood actor Heath Ledger who was found dead in New York two weeks ago returned home to Australia on Tuesday ahead of a private funeral expected later this week.

The cause of the 28-year-old's death remains a mystery, with a post-mortem inconclusive, a toxicology report yet to be released and conflicting speculation that Ledger was a drug user and suffering from pneumonia.

His father Kim Ledger, who returned to Perth from Los Angeles with Heath's mother Sally Ledger Bell and sister Kate, has described his actor son's death as an "accidental passing".

The family have spent the past two weeks in the United States where they held a Hollywood memorial service in Los Angeles, a private family service in New York and visited his Manhattan residence.

They flew back to Perth on Tuesday, but were immediately shepherded away from the waiting media.

"They literally had police around them," one passenger, who declined to be named, told the Australian Associated Press.

"They walked out of the plane, into the lounge and straight into the lift. That was it."

Ledger, 28, was found dead in his New York apartment on January 22.