A park ranger has been shot dead in a clash while patrolling in Sap Lanka Wildlife Sanctuary in Lop Buri province.
Karn Chaiprasert, 37, was found dead on Monday with a gunshot wound and a shotgun in his hand.
Wasant Klomchinda, head of the sanctuary, said Karn led a three-member team on a patrol at 1pm on Sunday in a forest on the Khao Ruak mountainside.
As night fell, they set up a checkpoint in the area, 3km from the sanctuary borders.
At 10am the next day, the team spotted three men with hunting gear. They tried to stop them but they fled deeper into the forest. A gunfire exchange ensued during the pursuit.
Kritsada Phet-nga, one of the team members, followed the sound and found Karn dead on a sharp slope 300m from the checkpoint. He informed the head of the sanctuary and the police.
Police later checked the scene and found casings, knapsacks, supplies and methamphetamine paraphernalia. They followed the trace of evidence for 2km to the border of the sanctuary but found no one.
Due to the rough terrains, it was not until 5.30pm on Monday that Karn's body was brought across hills to the town for an autopsy.
Prime Minister Prayut Chan-o-cha expressed condolences to Karn's family. He also ordered related agencies to provide aid for his family and told police to speed up their investigation, government spokesman Narumon Pinyosinwat said on Tuesday.
Police chief Gen Chakthip Chaijinda also expressed his condolences to Karn's family and pledged to solve the case as soon as possible.
Karn, a native of Si Thep district, Phetchabun province, joined the sanctuary a year ago after working at Thap Lan National Park in Prachin Buri and Nakhon Ratchasima provinces for 10 years. He was known for his courage and determination when performing his duty.
Sap Lanka, with 155 square kilometres (96,875 rai), is located in Lam Sonthi district, Lop Buri province. It is home to several breeds of wildlife such as fishing cats, leopard cats, wild boars and foxes.