The body of an unidentified man was found on Wednesday morning on a road over the ridge of an irrigation dyke in Muang district of Yala.
Police said the body was found at an irrigation dyke in tambon Sateng Nok.
The dead man, aged about 30, was shot once in the head. A spent cartridge case for a 9mm bullet was found near the body.
Police believed the man was captured elsewhere, then taken to the dyke and murdered.