It will be four weeks until Thai police will be able to conclusively say how American actor David Carradine died, officials said Saturday, as his body was flown back to the United States. The 72-year-old’s body was discovered Thursday morning hanging in a closet in a Bangkok hotel room. "(Forensic experts) will take three weeks to examine the toxicology tests and after that everybody concerned will meet to conclude the cause of death. It will take four weeks," said local police commander Somprasong Yenthaum. The star of 1970s TV series Kung Fu and the hit Kill Bill movies was in the Thai capital to shoot a film called Stretch . An initial autopsy report revealed Carradine died from a sudden lack of oxygen and his body showed no signs of struggle. The actor's body was being repatriated on United Airlines flight 890 that left Bangkok's Suvarnabhumi airport at 6:48am (2348 GMT Friday) bound for Los Angeles and New York via Tokyo, local media and officials said. Staff at the Nai Lert Park hotel, where Carradine had been staying, said the actor had entertained staff by playing a piano in the hotel lobby on three nights and seemed "very cheerful". Several former colleagues, including director Quentin Tarantino, have given interviews since Carradine's death to quash rumours that it was a suicide. Carradine was best known for his role as the fugitive half-Chinese Shaolin monk Kwai Chang Caine in the 1970s TV drama Kung Fu. But he failed to find great film success outside of cult "B movies" until Tarantino called on him to play the title character in the revenge-action films Kill Bill and Kill Bill II .