A special Supreme Court commission today heard a key witness testify that former president Ferdinand Marcos urged judges and prosecutors to conduct a sham trial and acquit those charged with the murder of Benigno Aquino Jr.

The chief prosecutor in the case, Manuel Herrera, told a special three-member commission appointed by the Supreme Court that Marcos summoned presiding Judge Manuel Pamaran and the prosecutors for a two-hour discussion at the presidential palace in January 1985 before the trial began.

He said that Marcos told him and the judge to conduct a moro-moro, or sham, trial. Moro-moro means an operetta in Tagalog, the Filipino language.

Herrera quoted Marcos as saying at the end of their meeting, "Thank you for coming. Thank you for your cooperation. I know how to reciprocate."

In October 1985, former armed forces chief of staff Gen. Fabian Ver and 24 soldiers and one civilian were acquitted of charges that they murdered Aquino in 1983.

Aquino's assassination pushed his widow, Corazon Aquino, into political life and eventually led her to seek the presidency. The controversial outcome of the presidential election on Feb. 7, in which Corazon Aquino contended that she was cheated, was followed by a military-led popular revolt and the ouster of Marcos. Corazon Aquino took power on Feb. 25 after Marcos and his party, including Ver, were airlifted by U.S. military helicopters into exile.

The Supreme Court created the commission to determine if the Aquino murder trial ought to be reopened. It acted on a petition by more than 30 prominent Filipinos, who argued that there had been a miscarriage of justice because of undue influence by Marcos.

As the Aquino murder trial was winding up, Herrera ceased to be involved in the case. At the time, he was quoted widely in local newspapers as saying that he already knew what the verdict would be.

Herrera said that he had recommended that all 26 defendants be charged as principals and be jailed but that Marcos told the prosecutors and the judge in the palace meeting to split them into different categories. He quoted Marcos as saying "the boys are frantic" that they might be sent to jail.

The soldiers were kept in a military camp. Eventually, 17 of the accused were charged as principals, Ver and seven others were charged as accessories, and the lone civilian was charged as an accomplice. This allowed those charged with the lesser crimes to post bail.

Under Philippine law, there is no appeal against an acquittal by the lower court, which was a special court set up to try civil servants. The law against double jeopardy also prevents a case being reopened.

But legal experts here said that a case can be reopened if it is proved that there has been a miscarriage of justice or that there had been collusion among trial officers.

Ver's counsel, Antonio Coronel, and the lawyer for most of the soldiers, Rodolfo Jimenez, said they will question the legality of the Supreme Court commission.