Thai exiles say they don't feel safe after the bodies of two other dissidents were found on a riverbank with concrete in their stomachs.
The Thai army said it has no knowledge of two critics of the military and royal family whose bodies were found "stuffed with concrete" along the Mekong River border with Laos.
DNA tests confirmed the two bodies, which were discovered late last month, belong to Chatcharn Buppawan, 56, and Kraidej Luelert, 46, Thai authorities confirmed on Wednesday.
The two were close aides to political activist Surachai Danwattananusorn, 78, who has been operating online radio programs critical of Thailand's junta and monarchy from Laos.
He also disappeared last month and is still missing.
The police said the cause of their deaths was unknown.
"There are no signs of bullet holes, but there is a wound in their stomach which has been cut open and stuffed with concrete and tied to make it sink. There are also no stab wounds," Police Major General Thanachart Rodklongtan said.
The activists' disappearance from Laos raised concerns among human rights groups that critics of the Thai monarchy and army are being targeted in exile.
A military officer, however, dismissed any idea of army involvement in the disappearances.
"This group of people live outside of our area or responsibility, we could not do anything," Lieutenant General Tharakorn Thamwinthorn said.
"It is clear now that we are in danger," Trairong Sinseubpol, another Thai activist in exile, said.
"Things are now very different ... Laos doesn't look that safe now."