The family of American actor David Carradine, who Thai authorities say died of risky sex play in a hotel room this week, has asked for an FBI investigation.
The 72-year-old actor was found dead in a Thai hotel room closet in an intricate web of ropes.
"It was neither suicide nor murder, he died after he had an orgasm," said Thailand's top forensics doctor Porntip Rojanasunan. "There was a rope tied around his neck and another rope tied to his genitals, and the two ropes were tied together and they hung in the closet."
The Thai policeman running the inquiry into Carradine's death said surveillance footage at Bangkok's Swissotel Nai Lert Park Hotel shows no one entered the room before the actor died, ruling out foul play.
Carradine's body was headed for Los Angeles from Bangkok via Tokyo today. An autopsy report will not be available for three weeks.
Friends told CNN's "Larry King Live" Friday night that they do not believe he committed suicide and were troubled by conflicting reports about how Carradine died.
The actor flew into Thailand last Thursday to work on the film "Stretch" and was found dead two days later. Friends told Larry King that Carradine could not have committed suicide because he was happily married, recently bought a new car and was involved in several other film projects.
"They want an investigation," said Mark Geragos, an attorney for brother Keith Carradine. "I would think that the people in Bangkok would want to support an investigation and allow the FBI to go over there and assist in the investigation so we can get the answers to the questions."
No suicide note was found, and Thai police said the actor may have died from accidental suffocation or heart failure from engaging in sex play known as auto-erotic asphyxia (AEA).
Sex experts say that Carradine's advanced age suggests that he may have been a lifelong practitioner of the secretive and dangerous practice, one that can go fatally awry.
Los Angeles Superior Court documents of Carradine's divorce put online by The Smoking Gun show that his most recent ex-wife, Marina Anderson, accused the actor of "deviant sexual behavior which was potentially deadly." The alleged behavior wasn't described in the court documents.
Also known as hypoxyphilia, the practice is a subcategory of sexual masochism that involves reducing the oxygen supply to the brain while masturbating to achieve a heightened orgasm.
Forensics experts say that sometimes the evidence of auto-erotic asphyxia -- a naked body in bondage -- can indicate murder. But often the victim has suffocated himself.
"If you hang yourself by the neck, you don't need so much pressure to kill yourself," said Rojanasunand. "Those who get highly sexually aroused tend to forget this fact."
"There's a fine line between the state of hypoxia [lack of oxygen in the brain] and death, and it's in that state that a person becomes highly aroused and it's what allows them to orgasm," said Eli Coleman, chair of the sexual health department at the University of Minnesota.
"People usually have safety nets and no intention to die, but something often goes wrong in their calculation," he told ABCNews.com. "Maybe a stool or something they are standing on somehow slips away."