The Department of Special Investigation (DSI) has reopened the stalled investigation into the murder of Japanese tourist Tomoko Kawashita in Sukhothai province in 2007.
Officials from the DSI, Region 6 Forensics Centre, and Central Institute of Forensic Science on Tuesday morning met at the Region 6 Forensics Centre in Phitsanulok to discuss the joint operation.
Investigators will focus on DNA samples and fingerprints of people who were near the scene of the murder.
Pol Lt Col Pong-in Inthornkhao, DSI deputy director-general, said they will take DNA samples and fingerprints from 152 more people. This would include about 60 border patrol police from Phitsanulok and 50 from Sukhothai.
The DNA samples would be taken at Chao Phraya Chakri camp of the 31st Border Patrol Police Sub-Division in Phitsanulok.
Kawashita, from Osaka, was found stabbed to death near Wat Saphan Hin in Sukhothai Historical Park on Nov 25, 2007. She was aged 27 at the time and was visiting the park to celebrate the Loy Krathong festival.
A BPP training course being held near the crime scene during the festival that year.
A reward of 500,000 baht was offered to anyone providing information leading to the arrest of the culprits.
Pol Lt Col Pong-in said authorities would continue their efforts to find the killer until the 20-year statute of limitations lapses.
Pol Gen Jaramporn Suramanee, a special cases adviser, said about 200 DNA samples had earlier been collected but none matched the DNA found at the murder scene.
He said the FTA paper technique now used by the CIFS, which is said to be more effective than other methods, would be used for the new round of DNA tests.
The reopened investigation follows a request from the Japanese embassy that Thai authorities step up their efforts to bring the killer or killers to justice.
In March this year, the murdered woman's parents, Yasuaki and Eko Kawashita, met then DSI director-general Suwana Suwanjuta, asking for a progress report on the case.