The parents of a Japanese woman murdered during the Loy Krathong festival in Sukhothai province in 2007 have asked the Department of Special Investigation to increase the reward for evidence leading to the killer's arrest.
Yasuaki and Eiko Kawashita made the request during a meeting with DSI director-general Paisit Wongmuang at the department's head office in Bangkok on Thursday.
The DSI earlier set its reward at 500,000 baht. Sukhothai police offered the same amount and the parents an additional 100,000 baht.
Mr Kawashita said the reward was too low and he had asked Thai authorities to raise it and increase the chances of someone coming forward with information.
Mr and Mrs Kawashita made a trip to the DSI two years ago and asked for a bigger effort in the investigation. With no obvious progress, they have now proposed increasing the reward.
Their daughter Tomoko was aged 27 when she arrived in Thailand alone from Osaka. She went to Sukhothai for the Loy Krathong festival. Loy Krathong day was Nov 24, 2007, and she was found stabbed to death in Sukhothai Historical Park the following day. A rented bicycle was beside her body.
Shortly before, she had emailed friends in Japan saying how much fun she was having and sent them many photos taken in Thailand.
Pol Col Paisit said the DSI had taken over the case in 2013 and the investigation had continued since then.
The DSI had checked all the clues it had, along with DNA profile tests of about 300 people who were near the crime scene at the time. No matches had been made with DNA traces found on Tomoko's clothing.
One recent clue indicated that another Japanese person was also near the crime scene. The DSI would ask Japanese police to contact that person for DNA comparison, Pol Col Paisit said.
Investigators relied on DNA tests because evidence from the crime scene was lost when the DSI accepted the case from local police six years after the murder, he said. The DSI would consider raising the reward, he said.
A Japanese diplomat lays flowers in 2014 at the place where the body of Tomoko Kawashita was found in Sukhothai Historical Park on Nov 25, 2007. (File photo)