The head of Boonchan Saipeth, 59, was found in a cardboard box on a road in Yala province's Yaha district, said police Maj. Suthas Nookhong. His body, with bullet wounds, was found in a house about 80 meters (yards) away, he said.
A note found with the body linked the killing to sectarian violence that has wracked the Muslim-dominated southernmost provinces since January last year, claiming more than 860 lives.
The killing, which police said took place sometime early Monday morning, came as a delegation from the Organization of the Islamic Conference was touring the province. The group is probing the causes of violence in the area.