A KHMER Rouge defector lined up a group of Vietnamese fishermen and opened fire on them to prove he was "fit to return" to the rebel group, locals of a small village near Phnom Penh say.
Two died and two more were injured in the December 9 attack in Prey Ampil commune, 15km north of the Capital.
The man - Hem Soka, 28, - felt he had to leave the commune when locals recognized him as the same man who, seven months earlier, had been hired as a "hit man" to murder another villager.
Fearful his former KR comrades would not welcome him back because of his defection, he decided to massacre some Vietnamese to win favor.
The events which led to the attack began in May, according to locals' statements to police, when two families in the commune had a quarrel.
One family hired Soka to come down from his nearby KR mountain base to murder a member of the other. He then went back to the jungle.
In September he and another KR guerrilla decided to defect. He returned to live in the commune, apparently thinking no one would recognize him.
Living with his girlfriend, he went unnoticed for several months. In early December, however, locals realized who he was and complained to their local court.
Man Lay, the Chief of Police of Khsach Kandal district, told the Post that Soka admitted killing a man when questioned but refused to appear in court.
Lay said Soka could not stay in the commune for fear of being killed by villagers or jailed.
However, he was also scared to rejoin the KR group he had betrayed by defecting.
He, his fellow defector and another friend armed themselves with three AK47s and a pistol - Soka had not turned in any weapons when he defected - and went looking for Vietnamese.
Locals said the men ordered several Vietnamese fishermen in boats to come ashore, and told nearby women and children to go away.
Four Vietnamese men were lined up on the river bank. Soka shot one of them before yelling "start", when his friends also opened fire.
Two of the four were wounded but reportedly managed to escape. The gunmen left the bodies of the other two lying on the ground as they fled back to the KR jungle base about 6km away.
Lay said the attack had prompted him to take a harder line against KR sympathizers in the village.
Soka's girlfriend might be charged with helping him to hide firearms.
Nineteen other villagers suspected of helping the KR had been asked to sign documents saying they would be taken to court if they continued to do so.
Ngnyen Ngoc Sang, vice-president of the Vietnamese Association in Phnom Penh, complained that local officials had ignored the survivors of the attack, offering them no help.
He said five Vietnamese families had moved from the commune, where they lived for nearly 10 years, to Phnom Penh the day after the attack.
The Vietnamese Embassy in Phnom Penh has condemned the shootings, demanding the Royal government bring the culprits to justice and do all it can to prevent any more such cases.