Three fisherman are being questioned on suspicion of murdering a British yacht skipper off southern Thailand's Andaman sea coast.
Malcolm Robertson, 64, was killed on Monday while sailing with his wife, Linda, near Koh Dong, an island about 45 miles west of Satun province, Thai Police said.
A spokesman said the men, migrant workers from neighbouring Burma, confessed to killing Mr Robertson after he caught them climbing onto his moored yacht in an attempt to steal a raft.
When Mr Robertson shouted for help they allegedly cut his throat before throwing his body overboard, the spokesman said.
The body has not been found.
Colonel Voradee Karawanont, of Satun Police, said: "Today we got a report from a fishing boat as the tragedy happened offshore. We tried our best to help but the murderers were not locals, they were from outside. We think in the future we will have more measures to make sure nothing like this happens again."
On a sailing internet blog, Mr Robertson tells how he and his wife left a marina in Eastbourne, East Sussex, in June 1998 to sail around the world. He described himself as the captain of the ship - named Mr Bean - and listed "Admiral Lindy Robertson" as his only crew member. Mr Robertson, who signed many of his blog entries as "Malc", charted his travels throughout 2007.
A spokesman for the Foreign and Commonwealth Office confirmed it is investigating the disappearance of a British man. Sources said Mrs Robertson is being treated in hospital for minor injuries.
Mrs Robertson's brother, John Clee, later said she was tied up and held hostage in the yacht's cabin for up to 12 hours.
He said she feared she would be killed too but instead she was left by the three men, who fled the vessel before being caught by police.
