The son of an influential local leader on Koh Tao has been cleared from possible involvement in the Koh Tao murder case after all four DNA test results showed no match.
The DNA samples taken from Warot Tuwichian did not match the DNA in semen retrieved from the body of British tourist Hannah Witheridge, who was raped and murdered on a Koh Tao beach, and items found at the crime scene, said police spokesman Prawut Thawornsiri late on Friday.
The four institutions which conducted the tests were the Police General, Ramathibodi, Chulalongkorn Memorial and Siriraj hospitals, he said.
"The results have been officially endorsed and there's no need to send more samples abroad to be retested.
"Mr Warot is not a suspect in the case but he has cooperated with us well. As far as the police are concerned, he was cleared long ago. We only did this [DNA tests] to comply with his wish to prove his innocence to the public," Pol Lt Gen Prawut said.
Mr Warot has been a subject of speculation and criticism in online media, in which he was suspected of being a perpetrator and the mastermind in covering up the crime.
Mr Warot is the son of Hat Sairee village chief Woraphan who owns AC Bar where the two murdered tourists had a quarrel with some men before being killed later that night.
Earlier, police arrested two Myanmar migrant workers on Koh Tao and charged them with the murders of the two British tourists.
Zaw Lin and Win Za Htun were charged with murdering David Miller, and killing and raping Witheridge. The suspects confessed during police interrogation but recanted their confessions on Oct 24, claiming they had been tortured by police to confess.
The police spokesman also said on Saturday his office would take legal action against the owner of the "CSI LA" Facebook page which has been critical of officers in connection with the crime.
"We found the Facebook page's administrator might want to destroy the credibility of Thailand's judicial process. The page is also linked to a political movement seeking to discredit the government, as reflected by its posts during the People's Democratic Reform Committee's anti-government protests in the first half," he said.
The general also claimed the page was created by a Thai citizen living abroad but was run by a team in Thailand.
"We already know who they are. We can't disclose more information at this stage because we're bringing them to be prosecuted under Section 14 of the 2004 Computer Crime act of which penalty is five years in prison or a fine of up to 100,000 baht."