According to the news report, Zinampan had been feuding with Valdez and last month had a fist-fight with her two sons and husband. Relatives said Zinampan had been threatening the family.

It is the latest in a series of killings to fuel public anger against the police.

Another police master sergeant, Jonel Nuezca, has been accused of cold-bloodedly murdering two neighbours, Sonya Gregorio, 52, and her son Frank, 25, in a dispute over noise in December last year.

Mobile phone footage taken by another neighbour shows an unarmed Gregorio and her son being shot twice at point blank range by a gunman who then saunters away. Nuezca has been dismissed from the service and detained pending trial.

‘Police act like kings’: anger in Philippines after killing of mother, son

In another incident, on May 23 in Valenzuela City in Metro Manila, police shot and killed an autistic 18-year-old who was out buying ice cream. Police claimed they were raiding an illegal cock fighting venue and had arrested the teenager when he tried to grab a policeman’s gun. The teenager’s family said he had simply been dragged to the venue and shot there. No video has emerged.

Zinampan, who was arrested on Tuesday morning, has admitted shooting Valdez. He told ABS-CBN News that he shot Valdez because of his simmering rage that her two sons had beaten him up.

“They didn’t respect me,” he said, asking for the family’s forgiveness. He admitted he had been drinking before he shot the woman.

The footage of the killing was taken by the daughter-in-law of Valdez, Julia.

Zinampan is assigned to the Police Security and Protection Group of the Philippine National Police.

The group describes its mission as to “secure and protect elected and appointed national government officials, members of the diplomatic corps and visiting foreign dignitaries, delegates and/or participants during special events [and] private individuals authorised to be given protection”.

Quezon City police have charged Zinampan with murder.

Footage has emerged on the internet showing an enraged Guillermo Eleazar, the chief general of the Philippine National Police, confronting Zinampan at Quezon City police headquarters following the killing.

It shows Eleazar yelling at Zinampan, “look at me – what were you thinking of when you did that?”, and grabbing him and shaking him against the wall.

The murder will be a test case for Eleazar, who assumed command of the problem-plagued national police force on May 8 vowing to purge it of “hoodlums in uniform”.

The Philippine National Police has been at the forefront of Duterte’s “war on drugs”, which human rights groups say has killed tens of thousands of Filipinos.

Duterte himself has several times publicly ordered the police to “shoot to kill” drug dealers and anyone “causing trouble” during quarantine.

Eleazar’s predecessor, Debold Sinas, was not highly regarded. In 2020 he held his birthday party in violation of the quarantine restrictions that his men were supposed to enforce. In the aftermath of the Nuezca shooting, he issued what sounded to many like a menacing statement warning people against filming policemen committing crimes.

Philippine police in spotlight after killing of mother and son

Critics say part of the problem is a flawed vetting process for police recruitment.

Manuel Mogato, a Pulitzer prize-winning reporter, said police recruits often managed to avoid taking the required neuropsychological tests by paying bribes or by leaning on their connections.

On Tuesday, Eleazar promised to reform the recruitment process to eliminate corruption.

Also on Tuesday, Filipinos were sharing a screenshot of a remark Zinampan made last year on his Facebook page, which is now unavailable.

“While there are unfortunate incidents like this, the vast majority of police perform their sworn duties everyday with honour and integrity to protect and serve the people,” Zinampan said.

Describing himself as someone who had served for 14 years, Zimpanan wrote: “I proudly defend the integrity of my uniform. I am proud to be a good cop.”