MANILA, Philippines — President Rodrigo Duterte's statement on Monday that the killing of a controversial Batangas mayor might be related to illegal drugs was just speculation, Malacañang explained on Tuesday.

Tanauan City Mayor Antonio Halili was shot dead in front of city employees and village officials during flag-raising rites at the city hall's parking lot on Monday.

Videos of the incident posted on social media showed his bodyguards returning fire on a grassy hill beside the parking lot which they suspected to be where the gunman was perched.

In a press briefing at the Palace, presidential spokesperson Harry Roque assured the public and the fallen mayor's family that the murder would be thoroughly and extensively investigated despite the suspicion of the president.

"I will quote from what the president said. Suspicion. It's only suspicion," Roque told reporters.

"I will quote what he said. It's a suspicion," he added.

Speaking in Southern Leyte, Duterte said that the murder of Halili could be related to illegal drugs. He also said that he believed Halili's supposed hard stance against drugs was just a front.

During his time, Halili paraded drug suspects through Tanauan City's streets wearing shirts or cardboard placards that read that they were drug dealers who should not be emulated. According to local reports, suspects in other crimes were also made to go on the "Walk of Shame."

This practice was criticized for depriving suspects of due process.

Police officials linked Halili to the trade of narcotics in the country, an accusation he denied. He also vowed to parade himself through his city's streets if this allegation was proven true.

On Tuesday, Angeline Halili, the slain mayor's daughter, said that the president had been fed wrong information. She said Duterte would see the truth if he visits them.

"I cannot blame our president for saying that if he was being given wrong information and information meant to hurt and malign people who are doing good," she said.

Roque: President's comments won't affect police probe

When asked if Duterte's pronouncement could affect the investigation and the public's perception of the mayor, Roque said, "I think no because he said it was just a suspicion while the investigation is yet to start. The promise of the government is there will be a thorough and extensive investigation to know who is behind the killing of Mayor Halili."

Duterte's spokesman also shot down suggestions that the military and the police could be involved in the shooting.

He also did not directly answer a question on the possibility that there was a culture of impunity under the administration.

"What we can assure you is we are discharging the state obligation for every murder. We will investigate and accord the victims adequate domestic remedy," he said.

He stressed that despite the president's suspicion, the Palace was alarmed by the killing, which was done in public and in broad daylight

Roque said that he had no information yet if Duterte would visit Halili's wake.