The family of a politician living in Prachin Buri province is believed to be responsible for encroaching on part of 10,000 rai at the world heritage-inscribed Khao Yai National Park, police said on Friday.
However further investigation is required to learn more details, said Col Pongphet Ketsupa, commander of an operation team of Internal Security Operations Command (Isoc).
He said his team is working closely with the Department of National Parks, Wildlife and Plant Conservation (DNP) to scrutinise areas that are thought to be illegally occupied, especially in Prachin Buri after other examples of encroachment were recently found there.
An initial probe determined that around 10,000 rai of land in Khao Yai had been encroached upon but the land owners have not yet been confirmed, he said.
"We believe the politician's family in Prachin Buri illegally occupied more land inside the forest. Our team is working hard to clear this up," he said, adding the support of the National Anti-Corruption Commission (NACC) has helped facilitate the investigation.
The NACC concluded on Tuesday there were sufficient grounds to launch legal action against Deputy Education Minister Kanokwan Vilawan, her father Soonthorn and eight other individuals for illegally occupying 150 rai in the national park.
Ms Kanokwan also serves as deputy secretary-general of the Bhumjaithai Party, while her father is the head of the Prachin Buri Provincial Administrative Organisation.
According to Col Pongphet, his team found the politician's family began illegally encroaching on the national park in 2017, when the Department of National Parks, Wildlife and Plant Conservation filed a complaint against them. But no progress was made in the case.
In 2020, the team found another 24 rai appeared to have been illegally issued to the same family. The case was sent to the Office of the Attorney-General for consideration.
Ms Kanokwan and her father claimed they purchased the land from its previous owners, but the NACC found the plots in question had never previously been used. The NACC concluded the family had colluded with government officials to illegally obtain the title deeds.
The Office of the Auditor-General (OAG) decided on Tuesday to indict 10 suspects in the matter and said it would forward the cases to the Region 2 office of the Criminal Court for Corruption and Misconduct Cases.
Four of the other suspects are Jeerasak Pholsuk, who once served as director of the Land Deed Surveying Centre in Saraburi, Nakhon Nayok, Prachinburi and Sa Kaeo provinces; Surang Kantarom, who once served as the survey director, Somsak Heeb-ngern who once performed the duties of surveying supervisor; and Phanphen Phakhayat, who acted as a land title investigator.
The remaining suspects are Prathan Banchuen, who formerly served as a land survey director; Tawee Muensri, a former village headman in tambon Noen Hom; Noi Tumphan, who was a survey leader; and Kanit Petchpradab, who used to be a surveyor under the Royal Forest Department.
As of Thursday, neither Ms Surang, Mr Somsak, Ms Kanokwan, Mr Soonthorn, Ms Noi nor Mr Kanit had presented themselves to prosecutors, prompting the issuing of arrest warrants.
Ms Kanokwan appeared before the prosecutor on Friday but her father has not reported himself to the OAG.
Officers from the Anti-Corruption Division and the Crime Suppression Division have joined forces to find Mr Soonthorn and the other remaining suspects before the charge expires on Monday.
DNP director-general Ratchada Suriyakul na Ayutthaya said he has instructed officials to scrutinise the Land Department.