The death of Albuera, Leyte Mayor Rolando Espinosa Sr. is a "big loss" to the Duterte administration's campaign against illegal drugs because he was a government "asset," Malacanang said on Sunday.

This as the Philippine National Police-Criminal Investigation and Detection Group (PNP-CIDG) has sent an investigating team to Leyte to probe into the death of Espinosa, who allegedly fought back authorities who were on a mission to enforce a search warrant against the late mayor early Saturday.

CIDG Director Chief Superintendent Roel Obusan formed the three-man team, which left Sunday morning for Tacloban City.

In an interview over a state-run radio station, Presidential Communications Office Secretary Martin Andanar admitted that personally he was puzzled by Espinosa's death.

"Mayor Espinosa (was) an asset to the government's investigation on those who were allegedly involved in illegal drug trade, especially those in the upper echelons of the drug ring," he told dzRB Radyo ng Bayan.

"That's why for me, Mayor Espinosa is a big loss to the government," he added.

Espinosa, who "surrendered" after he was included in the list of suspected narco-politicians of President Rodrigo Duterte, was arrested last October for illegal possession of firearms and explosives and for illegal drugs.

After giving up himself to PNP chief Director General Ronald dela Rosa, Espinosa reportedly became cooperative to the government on its fight against illegal drugs.

His son, Kerwin, who was also tagged in illegal drug trade, was arrested in United Arab Emirates. The Philippine government has been processing his return to the country to face charges.

Andanar cautioned that Kerwin's safety could be jeopardized if his security would not be handled properly.

"Kerwin, being the son of his father, I assume that he has information that is also vital for the government's investigation in the drug ring here in the country, particularly on narco-politics," he said.

Espinosa's death has prompted some senators to call for the resumption of the investigation on the alleged extrajudicial killings of suspected drug personalities. Senator Panfilo Lacson even called Espinosa's death as a case of extrajudicial killing.

"We respect Senator Lacson’s opinion. And we will also be guided by Senator Lacson’s wisdom. But then again, the Senate is an independent branch of government and let's wait on the next step of the Senate and the Palace will respect whatever the Senate or the Lower House, the Congress would decide on what to do," Andanar said. DMS