I feel so badly for David Carradine's family. From all signs it appears that his death was a result of autoerotic asphyxiation - a form of erotic bondage where the loss of oxygen to the brain creates its own kind of orgasm - but the family is having trouble accepting such a sordid fate for their patriarch, even after his ex-wife admitted finding him all naked and tied in knots frequently.
The family hired Dr. Michael Baden, one of the foremost forensic pathologists in the country, to perform an independent autopsy in the hopes of uncovering evidence that would point to foul play. There have even been rumors of a secret ninja cult assassinating him for knowing their secrets. (For what it's worth, Uma was not in the vicinity.) While his full report has not been released yet, Dr. Baden did tell Reuters that "(t)he cause of death was asphyxiation, an inability to breathe, now why that happened is still what we're working on."
Baden's investigation is continuing. He's still waiting for more information from Thai police before he can eliminate homicide as a cause of death, but I'd be surprised if anything was found. Like many other "gaspers", Carradine appears to have been a victim of his own deviant fetishes. It's a dangerous game and all too easy to overdo. It's also tragic that such a brilliant career should be overshadowed by such a senseless death.