Pol Maj Gen Songkiat Watakul, commander of Yala Provincial Police, said about 50 spent bullet cartridges had been collected from the scene, mostly scattered on a roadside dirt mound where the victims’ pickup truck stopped, and on the road.
An examination revealed the cartridges had been fired from five M16 assault rifles and an HK33, he said.
Three of the M16s had been used in four previous security-related cases in Krong Pinang and Yaha district, examination of marks on the spent shells showed.
The killers were believed to be insurgents active in the districts of Yaha, Krong Pinang and Bannang Sata, Pol Maj Gen Songkiat said.
The gunmen also took at least 50,000 baht in cash from the pickup before fleeing.
Southern security intelligence agencies believed the gruesome murder was the work of Hubaideelah Rommualee, a key insurgent of the rank of commander active in the three districts and his subordinate identified as Arbe jae Alee, reports said.