The Central Criminal Court for Corruption and Misconduct Cases granted bail for a former chief of Kaeng Krachan National Park and the three other suspects after they each placed 800,000 baht as a surety.
Chaiwat Limlikit-aksorn, former chief of Kaeng Krachan National Park, turned himself in at the Department of Special Investigation in Bangkok on Tuesday morning to answer a charge of murdering forest-based Karen activist "Billy".
At the same time, DSI investigators searched his house in Phetchaburi for evidence in the case.
Mr Chaiwat and three other suspects in the murder reported to investigators, as he promised on Monday, after the DSI obtained court warrants for their arrest in connection with the murder of Karen rights activist Porlajee "Billy" Rakchongcharoen, 31.
DSI officials started interrogating the suspects right away.
Mr Chaiwat, now the chief of Ubon Ratchathani-based Protected Area Regional Office 9, told waiting reporters he wanted to see the DSI's evidence. He wondered how the DSI had concluded its investigation into the Karen activit's disappearance in six months, learning all about the case, finding a human skull and finishing DNA examination.
He said he would cooperate, and then made a strange comment.
"Reports made me, (my) family and (my) organisation villains in the world of social media. I, as a defender of forests, no matter how big government officials are, if I can stand, I will definitely knock down all of them."
Mr Chaiwat accused media of causing him damage without waiting for proof.
"I and my subordinates are ready to fight. We will not flee because our families are here... I and my subordinates have devoted our life to forest protection," Mr Chaiwat said.
DSI director-general Paisit Wongmuang said investigators searched Mr Chaiwat's residence in Kaeng Krachan district of Phetchaburi on Tuesday morning for evidence in the Billy case.
DSI deputy chief Pakorn Sucheewakul said the suspects denied all charges but did not seek temporary release during the police interrogation.
After interrogating them for over three hours it was deemed necessary to detain the suspects for further interrogation, Pol Lt Gen Pakorn said.
Officers took Mr Chaiwat and the three other suspects in the case to the Central Criminal Court for Corruption and Misconduct Cases on Tuesday afternoon for approval for their further detention,
He also said DSI officers, armed with a court warrant, searched Mr Chaiwat’s Chai Ratchapruk residence. Drones were used to survey the 200-rai compound and a large pond inside it.
An initial survey showed the Chai Rachapruk residence was located in Yangnam Klad Nua and Yang Nam Klad Tai national forest reserves.
On Monday the Central Criminal Court for Corruption and Misconduct Cases issued arrest warrants for Mr Chaiwat and three others on suspicion they murdered Billy, who went missing in April 2014.
Porlajee disappeared while he was helping his relatives sue Mr Chaiwat for setting fire to their bamboo huts and rice barns during a series of forest evictions in the Kaeng Krachan National Park.
Two other suspects who work for state agencies, Bunthaen Butsarakham and Thanaset Chaemthet, also face charges brought by the DSI.
In addition to premeditated murder, the three are accused of detaining, robbing and threatening the victim with weapons, and concealing his dead body.
The other suspect, identified as Kritsanaphong Chitthet, is not a state official and is accused of supporting the trio's alleged crimes.
Porlajee was last seen alive on April 17, 2014, after Mr Chaiwat and his officials arrested the Karen activist for allegedly collecting wild honey in the forest.
Mr Chaiwat and park officials were earlier charged over the man's disappearance, but acquitted for lack of evidence.
After reopening the case in June, the DSI discovered skull fragments in an oil drum in the Kaeng Krachan reservoir that matched with the DNA of Porlajee's mother, and a murder investigation was launched.
Mr Chaiwat earlier disputed the DSI's finding, saying the DNA match did not prove the bones belonged to Porlajee.
The DSI is now working with experts to analyse 30 more bone fragments, as well as questioning over 100 possible witnesses.