A backpacker and musician has fled a Thai island where two young tourists were murdered after he claimed to have identified one of the alleged killers on social media.

Sean McAnna, 26, from Lanark, made the claim on Facebook yesterday following last week's deaths of Hannah Witheridge and David Miller, whose semi-naked bodies were found on a beach on Koh Tao after they were beaten with a hoe.

He also posted a picture of two swarthy moustachioed Thais one of which he said was the killer, a bar-resort owner.

Mr McAnna, who also contacted a television channel to make the claims, was given consular advice and protected by friends until he caught a ferry off the island.

The backpacker claimed on the website he was sitting on a rock near where the bodies of the pair were found. He went onto describe the island as having changed since he first visited it.

Mr McAnna added: "It's not the island I used to know... But I know Koh Tao will continue to be the paradise island it always was. Especially now. I've spoken to girls who are heart-broken about this, but have said that nothing will stop them living the free, island life. And fair play to them, this has been the first westerner's killing in a decade. And will be the last, hopefully. It's a life we know and will always attempt to strive for."

The comments came after Thai police said DNA testing had failed to reveal a match for the killings of Ms Witheridge, 23, from Great Yarmouth, Norfolk, and Mr Miller, 24, from Jersey. However, a spokesman said they had only so far tested migrant workers and people in service.

Police are still awaiting the results for the tests of a speedboat driver who it is claimed was hiding in a cave. The 28-year-old is being held in Koh Tao on drug charges after testing positive for a substance.

But police do not think there is a link between the man and the killings. Officers are working on a new theory of 'sexual jealousy' having identified DNA from the blood-stained hoe. They have asked the Metropolitan Police to contact Ms Witheridge's friends to find out if they knew anything about any relationships she had before her death. There are also unconfirmed reports Ms Witheridge and Mr Miller had a fight in a bar with a Thai man before their deaths.

The last foreigner to be murdered about 10 years ago was a confrontational dive resort owner.

But the Samui Archipelago is not exactly positioned in a sea of tranquillity and a Foreign Office advisory gives a warning of muggings, rapes and people going insane on drugs.

A short-term resident foreigner who had strived for the island life left Koh Tao to write blog entitled 'Koh Tao - The Murky Truth' stating: 'There were several killings..murders, when I stayed there.

"After a few weeks on the island, we found out that Koh Tao has a dark underbelly in the form of locally powerful mafia-like families that own many of the businesses and make sure that they get the cream of the profits that tumble into Koh Tao.

"In the fairly short time we were there, several people were killed - that is, murdered.

"We even heard the crack of a gunshot on one occasion."