A suspect for the murder of six-year-old beauty queen JonBenet Ramsey left Thailand on a flight to the US last night to face charges in connection with her death.

John Mark Karr, with three US officials as escorts, was put on board Thai Airways International flight TG794 bound for Los Angeles from Don Muang International Airport.

Karr is to end his journey in Boulder, Colorado, where he faces charges of first-degree murder, kidnapping and child sexual assault in connection with the 1996 killing.

The 41-year-old school teacher sat in a business class window seat next to Mark Stray, an investigator with the Boulder District Attorney's office. A US Embassy official and a security officer with Homeland Security emblazoned on his T-shirt were also part of the escort party.

Before take-off, Karr, who was not handcuffed, took a glass of Champagne from a cabin attendant and clinked classes with Stray, who had selected an orange juice.

Just hours before his departure a doctor at Pratunam Polyclinic, which specialises in sex-change operations, admitted Karr was one of his patients.

Karr, who is not charged with any crime in Thailand, is being expelled from the country because he is regarded as an undesirable person. He is not being extradited.

Karr, once detained on charges of possessing child pornography, in recent years apparently travelled to Europe, Central America and Asia to search for teaching jobs.

He was arrested a day after he began teaching second grade children in Bangkok, US prosecutors said.

When Karr spoke to reporters last week, he said he was alone with JonBenet when she died in the basement of her home on December 26, 1996, but that her death was an accident.

Although Karr took responsibility for the girl's death, his statements have been sketchy, and with little public evidence linking him to the crime, some experts have speculated that he is either lying or delusional.