Vice President Sara Duterte is set to confront two of the principal figures behind the allegations against her after naming former senator Antonio Trillanes IV and self-confessed former aide Ramil Madriaga as witnesses for the defense in her impeachment trial before the Senate.

In a pre-trial brief submitted to the Senate impeachment court on 15 June, Duterte's legal team identified 17 witnesses and outlined the evidence it plans to present in response to the Articles of Impeachment.

“Since the burden of proof never shifts, it is incumbent upon the Prosecution to prove their allegations in the Articles of Impeachment,” the defense panel’s pre-trial brief read.

The Articles of Impeachment approved by the House accuse Duterte of culpable violation of the Constitution, graft and corruption, betrayal of public trust, bribery and other high crimes.

“Until the prosecution is able to present any such credible, competent, and admissible evidence, the respondent reserves the right to present additional controverting evidence,” it added.

Madriaga previously testified before the House Committee on Justice, identifying himself as a former aide and alleged "bagman" of Duterte. 

He claimed that P125 million in confidential funds from the Office of the Vice President was allegedly disbursed in less than 24 hours upon Duterte's instructions.

Trillanes, meanwhile, submitted an affidavit and testified before House proceedings, accusing the Duterte family of amassing ill-gotten wealth and maintaining undeclared assets and bank accounts. 

The former senator is likewise part of the House prosecution panel's witness list.

Aside from Trillanes and Madriaga, Duterte's witness list includes officials and representatives from the Office of the Executive Secretary, Office of the Ombudsman, National Bureau of Investigation, Anti-Money Laundering Council, Department of Foreign Affairs, Bureau of Immigration, Land Transportation Office, Philippine Statistics Authority and several financial institutions.

For its part, the House prosecution panel has assembled more than 30 witnesses for the impeachment trial.

Lead prosecutor and Batangas Rep. Gerville Luistro earlier said the prosecution's witness lineup includes Trillanes, Madriaga, officials from the Commission on Audit, AMLC representatives, investigators and other individuals expected to testify on allegations involving confidential funds, unexplained wealth and other charges cited in the impeachment articles.

The prosecution is also expected to present Commission on Audit findings, AMLC records, government documents, whistleblower testimonies and evidence gathered during congressional investigations.

Duterte has repeatedly denied wrongdoing and described the impeachment case as politically motivated.

The Senate, sitting as an impeachment court, will ultimately determine whether the vice president should be acquitted or convicted. 

A conviction would require the vote of at least two-thirds of senator-judges and would result in her removal from office and perpetual disqualification from holding any public office.