Pol Col Tanongsak Wangsupha, deputy chief of Pattani police, said Chao Rattanasan, 67, an employee of the 44th Military Development Unit's animal husbandry centre in Thung Yang Daeng district, was killed while travelling on a motorcycle along the Khok Pho - Chang Hai Tok road.
He was followed by two men on another motorcycle. The pillion rider opened fire at him with a pistol, hitting him in the head. He died on the spot.
Police were trying to establish the motive for the killing.