The man suspected of murdering Japanese tourist Tomoko Kawashita in Sukhothai 12 years ago has died, Justice Minister Somsak Thepsutin said on Wednesday.
The 32-year-old murder suspect, whose name was not revealed, was poisoned in 2010, three years after he stabbed Kawashita to death in the Sukhothai Historical Park, Mr Somsak said on Wednesday, after meeting Japanese police and officials from the Japanese embassy.
The minister said the information had been passed on by a friend of the murder suspect. The friend claimed that during a drinking session, the suspect had brandished a weapon and confessed, "This knife was used to attack Tomoko," Mr Somsak said.
Following up on the claim, Department of Special Investigation (DSI) officials travelled to Sukhothai in the hope of taking a DNA sample, but found the suspect's body had been cremated, Mr Somsak said.
"Investigators will instead collect DNA samples of the suspect's sister and all workers at a [nearby] pig farm for testing," said the minister.
The investigation will also cover people with a record of robbery or drug addiction, as the suspect had been addicted to drugs and alcohol.
DNA samples collected will be examined to find whether they match DNA left on Kawashita's clothes.
The murder suspect escaped DNA tests conducted soon after the gruesome murder, as police only checked suspects living within 200 metres of the crime spot, Mr Somsak said.
He expects the new DNA test results by Nov 15.
Kawashita, 27, arrived as a solo traveller in Thailand and visited Sukhothai for the Loy Krathong festival on Nov 24, 2007. She was found stabbed to death near Wat Saphan Hin in Muang district the following day.
The DSI took over the case in 2013 after local police failed to make progress.
Mr Somsak said few Japanese travellers had visited the province after learning of the murder.
Before the incident, around 10,000 Japanese tourists visited Sukhothai annually.