Human Rights Watch called on Thai authorities on Wednesday to immediately find the murderer of environmental activist Prajob Naowa-opas, who was shot dead in front of witnesses in Chachoengsao on Monday.
"The cold-blooded killing of Prajob marks yet another example of the fundamental failure of Thai authorities to protect activists who risk their lives while defending their communities," Brad Adams, Asia director at Human Rights Watch, said.
"The government must undertake a serious investigation to bring those responsible for his death to justice, regardless of the status or political affiliation of the killers."
Prajob was shot several times by a gunman around 1.10pm on Monday at a garage in Phanom Sarakham district where he was waiting for mechanics to finish working on his pickup truck, according to police.
Environmental activist Prajob Naowa-opas.
The 43-year-old activist died on his way to a hospital. The gunman, who fired four bullets from an 11mm handgun, fled the scene in the same car he and a companion arrived in.
Immediately after his murder, Chachoengsao police said they would not rule out either a business conflict or his active campaign against factories polluting areas in Phanom Sarakham and Plaeng Yao districts as a possible reason.
Prajob, who was the village chief of moo 14, tambon Nong Haen, Phanom Sarakham district, had set up a landfill company in the central province.
But Pol Maj Gen Niwat Rattathammawat, deputy chief of the Provincial Police Region 2, said on Tuesday that Prajob's public exposure of and active opposition to toxic waste dump sites was the probable cause
Prajob had led villagers in a campaign exposing the dumping of toxic industrial waste in the two districts since February last year. Many ponds have been filled with dangerous chemicals from factories.
According to the Chachoengsao provincial public health office, water sources and farmland have been contaminated by a wide range of toxic substances - including carcinogenic phenol at a level 30 times the safety limit.
The dumpsites are primarily located on high ground, resulting in toxic waste running off and entering waterways and ponds.
The Department of Special Investigation (DSI) decided in August to take up the issue as a special case.
Prajob knew that his life was in danger after the campaign and carried two guns in his truck, Pol Maj Gen Niwat said. Police had already warned him he was a target but he had not requested police protection, he said.
Pol Maj Gen Niwat said after investigators believed the murderer was a professional gunman. He had calmly got out of the car, walked towards Prajob and killed him. Professional hitmen commonly use an 11mm pistol, he added.
A security camera recorded images of the vehicle used by the killer, he said, and police are questioning all witnesses and looking at other evidence in tracking down the gunman.
It was the same car believed to have shadowed him to his house and construction sites for months, the officer said.
Since 2001, more than 30 human rights defenders and environmentalists have been murdered in Thailand.
A picture from a closed-circuit security camera shows the vehicle used by the gunman who killed Prajob Naowa-opas, an environmentalist, in Chachoengsao. (Photo by Sonthanaporn Inchan)