Senate President Alan Peter Cayetano on Saturday questioned the credibility of the investigation into the armed standoff inside the Senate, arguing that the National Bureau of Investigation and the Department of Justice cannot credibly investigate an incident in which they were directly involved or had operational awareness.

At the center of Cayetano’s criticism was what he described as an inherent conflict of interest in allowing law enforcement agencies to lead the probe into the 13 May security incident, where gunfire erupted between Senate security personnel and NBI agents during a disputed operation linked to an alleged International Criminal Court arrest warrant.

“If you want to be the good guys or you want to be the bida, you cannot be the kontrabida,” Cayetano said.

“It is clear: you cannot say you will investigate to find the truth when you yourself are the one who should be investigated,” he added.

Cayetano said the situation undermines public confidence in the inquiry, noting that the NBI—an attached agency of the DOJ—was directly involved in the confrontation, while senior DOJ officials allegedly had prior knowledge of operational movements related to the incident.

The standoff occurred inside Senate premises on Wednesday night after NBI personnel reportedly entered the compound amid efforts to serve an alleged ICC-linked arrest warrant against Senator Ronald “Bato” dela Rosa. 

The Senate’s Office of the Sergeant-at-Arms (OSAA) said its personnel fired warning shots during the encounter, while law enforcement agencies have denied carrying out an arrest operation and disputed claims that their agents discharged firearms.

Reports from security sources placed OSAA warning shots at 27 rounds, while NBI agents were alleged to have fired five rounds. 

Cayetano also questioned Justice Secretary Frederick Vida’s admission that he had prior awareness of NBI movements on both Monday and Wednesday, saying this further raises doubts about the department’s neutrality.

“It’s the other way around; you should be part of those being investigated. If you knew [about the NBI’s actions], why didn’t you speak up?” he said.

The controversy stems from a broader dispute over the attempted service of an ICC-linked warrant involving Dela Rosa, who resurfaced in the Senate earlier this week amid heightened political tension and leadership changes in the chamber.

The ICC, based in The Hague, is investigating alleged crimes against humanity connected to the Duterte administration’s anti-drug campaign. Philippine authorities have yet to clarify the scope of cooperation in the disputed enforcement action regarding dela Rosa's warrant of arrest.

Cayetano said the incident as an issue of institutional integrity, stressing that law enforcement agencies cannot conduct uncoordinated operations inside a co-equal branch of government.

“We’re protecting the integrity of the Senate, the integrity of our Philippine Constitution,” Cayetano stated.

Despite the disruption, he confirmed that the Senate proceeded with the transmission of the Articles of Impeachment against Vice President Sara Duterte and is set to formally convene as an impeachment court on Monday.

He rejected claims that the leadership transition and ensuing events were intended to derail the proceedings, saying the Senate continued to perform its constitutional duties despite what he described as an atmosphere of tension following the standoff.