BANGKOK, Dec. 12 (Xinhua) -- A Thai police officer has been arrested on charge of killing a Frenchman following a brawl in Sukhumvit area of Thailand's Bangkok.

Immigration Bureau Commissioner Surachate Hakparn said on Wednesday that the policeman-turned-gunman, identified as Police Warrant Officer Kantapong Huadsri, attached to Lumpini police station, had fatally shot the French national, only identified as Malik, 35, in the head at a shophouse in Sukhumvit 13 area of Watthana district on Tuesday night.

The two of them had engaged in a fistfight at a bar in the neighborhood shortly before the policeman followed the Frenchman to his place and killed him with his gun in the presence of the deceased's girlfriend, according to the commissioner.

The police warrant officer turned himself in at Lumpini police station and admitted to the murder charge.

The case is still under investigation as report said there was another man coming to the scene with the policeman-turned-gunman, Thai police said.