Washington ? Out of jail after 85 days, New York Times reporter Judith Miller testified before a grand jury Friday, setting the stage for prosecutors to decide whether to charge anyone in the Bush administration in the leak of a CIA operative’s name.

Miller, who had been in jail for refusing to testify, was the final holdout witness whose testimony Special Counsel Patrick Fitzgerald said he needed before concluding down the probe into who leaked the identity of Valerie Plame.

Miller said she got assurances from her source and from Fitzgerald that enabled her to testify.

“I know what my conscience would allow and … I stood fast to that,” the reporter said as she emerged from the federal courthouse where she spent more than four hours, most of it behind closed doors testifying.

Before she agreed to talk to the grand jury, Miller’s source, Vice President Dick Cheney’s chief of staff, Lewis “Scooter” Libby, gave her assurances she could reveal the contents of their conversations. For his part, Fitzgerald promised to limit his questioning of Miller to the Libby contacts.

Fitzgerald has characterized Miller’s testimony as key to completing his investigation into the White House role in the disclosure of Plame’s identity. The grand jury expires Oct. 28.

Fitzgerald exited the courthouse without commenting, except to tell reporters, “I’m leaving.” Fitzgerald’s spokesman, Randall Samborn, declined to comment about what would happen next.

Until a few months ago, the White House maintained that Libby and presidential aide Karl Rove were not involved in leaking the identity of Plame, whose husband had publicly suggested in July 2003 that the Bush administration twisted intelligence in the run-up to the war in Iraq.

When former Ambassador Joseph Wilson made his allegation the White House was already on the defensive as it sought fruitlessly to find any weapons of mass destruction in Iraq. The president’s claims of such weapons had been the main justification for going to war.

Miller, released from jail Thursday night, had been in custody in Alexandria, Va., since July 6. A federal judge ordered her jailed for civil contempt of court when she refused to testify.