Malacañang on Thursday reminded senator-judges to remain impartial in the impeachment trial of Vice President Sara Duterte, following observations that some appeared to be acting as members of the defense panel.

Palace Press Officer Claire Castro said senator-judges should be guided by the law and the evidence presented before the impeachment court.

"Kung ano ang sinasabi ng batas at ng ebidensya, sana huwag walisin at pahinain ang katotohanan at ilihis kung ano ang sinasabi ng batas. Marami kasing lumalabas sa impeachment, ayon sa PCO, na nag-aaktong lawyer na hindi dapat. Dahil dapat manatiling impartial at walang bias ang mga senator-judges. Hindi nila mandatong walisin ang katotohanan. Huwag silang magdala ng walis sa Senado," Castro said.

A trial lawyer herself, Castro said senator-judges are expected to ask clarificatory questions rather than cross-examine witnesses.

"Judges should ask for clarification, asking clarificatory questions and not to cross-examine the witness. They should not be involved in a debate with the witness, as their mandate is to uncover the truth and not to cover up," she said.

Castro declined to identify the senator-judges she was referring to but said it was apparent that some had extensively questioned prosecution witnesses.

The remarks came after a tense exchange during the 13th day of Duterte's impeachment trial between Sen. Imee Marcos and prosecution witness Roderick Wamil, an auditor from the Commission on Audit.

Marcos questioned Wamil on the implications of a notice of disallowance involving the Office of the Vice President's confidential funds. Wamil explained that, under the joint circular governing confidential and intelligence funds, a notice of disallowance creates a prima facie presumption that funds were used for personal benefit if documentary requirements are not met.

When asked whether COA had found the acknowledgment receipts or supporting documents to be fake or forged, Wamil said determining their authenticity was beyond the scope of the agency's compliance audit.

The Senate impeachment court is currently hearing Article II of the Articles of Impeachment, which includes allegations of unexplained wealth, failure to properly disclose assets in Duterte's Statements of Assets, Liabilities and Net Worth from 2022 to 2024, and failure to divest business interests.