National Bureau of Investigation (NBI) director Melvin Matibag on Tuesday defended his decision to testify in Vice President Sara Duterte’s impeachment trial, saying that his wife’s support for the impeachment effort was separate from his duties as head of the country’s top investigative agency.

Matibag faced questions from Duterte’s defense counsel Mark Vinluan over a potential conflict of interest after acknowledging that his wife, Laguna Rep. Ann Matibag, had endorsed the impeachment complaint against Duterte.

“I am not a member of the Committee on Justice of the prosecution. However, the job of my wife as a legislator is totally detached from me being the director of the National Bureau of Investigation,” Matibag told the Senate impeachment court.

Vinluan raised the issue while challenging Matibag’s credibility as a prosecution witness, arguing that his testimony involved an investigation of Duterte while his wife had publicly supported the proceedings seeking the Vice President’s removal from office.

Matibag, however, said his testimony was based solely on his mandate as NBI director and was not influenced by his wife’s political position. The NBI chief was called to testify on the bureau’s investigation into Duterte’s November 2024 remarks in which she said she had spoken to someone about a plan to kill President Ferdinand Marcos Jr., First Lady Liza Araneta-Marcos and former House speaker Ferdinand Martin Romualdez.

Pre-testimony meeting

During cross-examination on Tuesday, Duterte’s defense counsel Mark Vinluan asked Matibag whether he coordinated with the prosecutors before appearing at the Senate impeachment court.

Matibag admitted that he met with members of the prosecution panel, including House Deputy Majority Leader and Lead Prosecutor Gerville Luistro, before appearing before the impeachment court.

“You mean prior to your appearance in this Honorable Court, you met with certain members of the prosecution?” Vinluan asked.

Matibag, however, denied that the meetings amounted to coaching, saying they only covered the matters expected to be discussed during his testimony. He added that such a meeting was not unusual and that he would also be willing to sit down with the defense if they chose to present him as a witness.

The defense also questioned whether Matibag appeared before the tribunal under a subpoena or merely through an invitation from prosecutors. Vinluan pressed the NBI chief on the matter, noting that questions remained over the basis of his appearance.

The NBI chief said he appeared after being identified as a witness in the impeachment proceedings and being invited by the prosecution and the impeachment court.

Luistro had earlier identified Matibag as the prosecution’s final witness for the alleged threat charge, saying his testimony would complete the panel’s presentation on that article.