The rules being applied to Vice President Sara Duterte's Senate impeachment trial theoretically allows both the prosecution and defense side to present "surprise" witnesses in the sense that they were declared, but their identities were kept under wraps.

This can be gleaned from the statements made by House prosecution team members Batangas 2nd district Rep. Gerville "Jinky Bitrics" Luistro and San Juan City lone district Rep. Ysabel Maria Zamora in a press conference Monday, June 15.

Incidentally, the prosecution panel will be filing its pre-trial brief today wherein it will declare before the Senate impeachment court its pieces of evidence and list of witnesses, among other things.

“While the general rule is that we have to list down all of the names of the witnesses that we will be presenting during trial, we are allowed to withhold certain names for security and safety purposes,” Zamora said.

The clarification came after reporters asked whether or not bank officials would be among the witnesses tapped to testify by the prosecution in support of allegations involving Duterte's alleged unexplained wealth.

“So, regarding the bank officials, for example, it is possible that we will not yet say the names of these persons, but there will be a description of their position and or the purpose of their testimony,” Zamora said.

Luistro, the lead prosecutor in the high-stakes case, said this rule applies "not only to witnesses, it applies even to documents which are not yet available during the conduct of pre-trial".

“In simple terms, the parties are allowed to make a reservation in the pre-trial brief and during the pre-trial conference, provided we give a reasonable description of who this witness is, what will be the nature of the testimony, and what is the purpose to be achieved by presenting this witness,” she said.

The prosecution panel was yet to formally file it's pre-trial brief during the press conference. Monday was the deadline for the filing of the pleading,

At any rate, Luistro said more than 30 witnesses would be presented in the quest to convict Vice President Duterte.

"It is more than 25. The witnesses is not only 25, it’s not only 30, it’s even more,” said the Batangueña.

She says that generally speaking, witnesses whose names are not disclosed during pre-trial proceedings may be barred by the Senate impeachment court from testifying later.

The pre-trial brief will contain the prosecution’s list of witnesses, proposed stipulations of fact and documentary evidence that will be presented before the impeachment court.

Luistro said bank representatives and bank records have long been considered part of the evidence the House intends to present in the impeachment proceedings.

“We have no communication with the bank officials, but since the proceeding in the Justice Committee, it has always been the intention of the House of Representatives to include the bank representatives and the bank documents among the evidence which will be presented by the prosecution team,” she said.