A key witness for the prosecution in the murder trial of Westchester actor Lillo Brancato Jr. took the stand Friday, testifying against his former friend and drug client.

The prosecution claims Joseph Borelli saw the ?Sopranos? star and his alleged co-conspirator, Stephen Armento, moments before Officer Daniel Enchautegui was killed. Borelli insists the actor was aware Armento had a gun in his possession.

Borelli, who had been previously convicted for crimes ranging from drug possession to attempted murder of a police officer, agreed to testify against Brancato so he could get a reduced sentence on a federal drug charge. Borelli told jurors Friday that he used to sell the actor seven bags of heroin each day.

According to prosecutors, on Dec. 10, 2005, Brancato and Armento were not able to find drugs at a home next door to off-duty Officer Enchautegui. So they went to Borelli's house, but Borelli claims he chased them off his property after Armento threatened him with a gun.

The two men then allegedly returned to the first house, where they encountered Enchautegui, and Armento fatally shot the officer.

PBA President Patrick Lynch says he hopes the jury will find Brancato guilty of the same crime as Armento, who was convicted of first-degree murder in October and sentenced to life without parole.

?They both participated in burglary, they participated in the death of a hero police officer,? he says. ?He will go to prison. This jury sees that.?

Testimony in Brancato?s murder trial continues Monday.

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