MANILA - Authorities have finished an autopsy on the remains of slain Tanauan Mayor Antonio Halili, an ABS-CBN News source said Tuesday, a day after the local official was shot dead during a flag-raising ceremony.

Halili, who was on President Rodrigo Duterte's list of allegedly narcotics-linked officials,was hit in the chest by a single shot fired from a distance. The shooter escaped.

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The shot hit Halili's heart while fragments of the bullet damaged his internal organs, the ABS-CBN source said of the initial autopsy findings.

The bullet fragments have been submitted to the Regional Crime Laboratory at Camp Vicente Lim in Calamba, Laguna, the source said.

The mayor's remains have been brought to his house in Barangay Sambat, Tanaun for a public viewing, where his constituents and supporters have flocked.

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Halili had gained prominence for introducing a "walk of shame" parade of alleged drug dealers through Tanauan.

However, Halili was stripped of his supervisory powers over local police in October 2017 due to a proliferation of illegal drugs in his city, amid allegations by the national police that he may have been involved. Halili denied the allegations.

Duterte's spokesman, Harry Roque, vowed justice for the mayor, describing him as a "staunch advocate against illegal drugs".

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Duterte, however, slammed Halili, saying the latter pretended to be an anti-illegal drug crusader to cover up his supposed involvement in the narcotics trade.

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With reports from Noel Alamar and Fay Virrey, ABS-CBN News; Agence France-Presse and Reuters