Thammayut Sangrod, 57, was fatally shot in the right chest and face at the palm plantation in tambon Nakha on Monday night, Pol Col Somdej Sukkarn, chief of Khao Phanom police station, said on Tuesday.
The plantation was run by Thai Pattana Co, a joint operation by a foreign investor and his Thai business partner, who recently died. There is nobody managing the plantation, which has no land ownership papers. Local residents and outsiders are trying to occupy the property.
The victim was a close relative of the kamnan of tambon Nakha, and was attacked while leaving the farm on a motorcycle, Thai media reported on Tuesday.
Local residents took him to a nearby hospital where he was later pronounced dead.
Pol Col Somdej said police believed the land conflict was the likely motive for the killing, as there were at least four groups numbering hundreds of people trying to seize the land, according to Thairath Online.
Thammayut had led one group of residents that had occupied the land.
Police were investigating.