PHNOM PENH, Cambodia (AP) — Cambodian police said Saturday that they were looking for four suspects in the beating death of a journalist whom human rights groups suspect may have been killed because of his work.

Mom Hun, chief of police in central Kampong Chhnang province’s Cholkiri district, said Suon Chan was at home drinking with a friend Jan. 31 when an argument began with the suspects as they walked past. It turned into a fight, with both sides using stones and sticks, and the journalist died in a hospital two days later.

The Cambodian Center for Human Rights said it was suspected that Suon Chan was killed for reportedly writing in the newspaper Meakea Kampuchea about illegal fishing, but Mom Hun said it was unclear whether he was targeted for that reason or simply became involved in a drunken brawl.

“Suon Chan is the 12th journalist to have been killed in Cambodia and the first since Hang Serei Oudom was murdered in September 2012 in Rattanakiri province,” the group said in a statement. “The majority of these deaths have not been properly investigated, with the perpetrators still at large and rewarded with complete impunity for their crimes.”

The New York-based Committee to Protect Journalists also called for Cambodian authorities to identify the motive behind the killing and to ensure the assailants are brought to justice.