Authorities were holding two men Monday after the murder of a deputy chief of military police, officials said.
Col. Reth Nika, 27, was gunned down on a busy Phnom Penh street Sunday evening. He had fled his Mercedes after it was chased by an SUV and became stuck in traffic, Agence France-Presse reported Monday.
Gunman ran after Reth Nika and caught up with him in a pagoda, where they shot him dead, AFP reported.
Two suspects had been arrested and a third man thought to be involved died from injuries sustained during a shootout, Phnom Penh Police Chief Touch Naroth said. Police suspected a personal grudge and were searching for two more suspects, he said.
AFP reported the dead assailant as Rath Sorady, 20, a policeman with the Interior Ministry.
Keo Remy, first vice president of the Human Rights Party, called the shooting a "brutal" example of the "killing anarchy" brought about by weak rule of law.
Chan Saveth, an investigator for the rights group Adhoc, said his group was investigating the shooting.