Authorities identified the victim as Police Officer 1 Mariano Briol, 28, married, of Sun Valley Subdivision, Barangay San Valley, Parañaque.
The victim was shot in the right temple with the bullet exiting through the left side of his head, killing him instantly.
Case investigator P02 Ramil Padios said the suspect, an alias Kim Batugan, took the victims service firearm before fleeing the crime scene.
The suspect is now the subject of a police manhunt.
Initial investigation showed that the incident happened at around 4:30 p.m. along the seawall at Baclaran after Briol had just visited friends in the area.
A lone witness told authorities the police officer, who was in a Type C PNP uniform (white shirt and the blue PNP pants), was waiting for a ride home when the suspect casually approached him and without warning shot him in the head.
An empty shell of caliber .38 pistol was recovered from the crime scene.
Padios said old grudge and revenge are the strongest possible motives in the killing of Briol.
Briol was assigned last year in Baclaran and belonged to a team in charge of clearing the sidewalks of illegal vendors. During one operation, Briol had apprehended the suspect, whom authorities have identified as the head of a syndicate that serves as protector to sidewalk vendors. Nikko Dizon