Judith Miller (file photo)

New York Times reporter Judith Miller testified before a grand jury in Washington Friday in connection with the leak investigation involving the Bush White House and a covert CIA operative. Ms. Miller testified only hours after she was released from jail for refusing to cooperate with the grand jury.

Judith Miller told reporters outside a federal courthouse in Washington that she was glad to be free after spending 85 days in jail for refusing to testify in the probe of whether high-ranking White House officials were involved in leaking the identity of covert CIA operative Valerie Plame.

Ms. Plame is married to former Ambassador Joseph Wilson, who accused the Bush administration of twisting intelligence in advance of the U.S. led invasion of Iraq.

Leaking the identity of a covert intelligence agent is a federal crime and a special prosecutor is probing whether high-ranking White House officials revealed Ms. Plame's identity as a way of getting back at Ambassador Wilson.

Ms. Miller testified before the grand jury investigating the case for several hours Friday.

She says she changed her mind and agreed to testify after her source urged her to cooperate with the leak probe. "Recently, I heard directly from my source that I should testify before the grand jury. This was in the form of a personal letter and, most important, a telephone call to me at the jail. I concluded from this that my source genuinely wanted me to testify," she said.

Ms. Miller would not identify her source. But her newspaper, the New York Times, identified him Friday as Lewis Libby, chief of staff for Vice President Dick Cheney.

Ms. Miller never wrote a story about the Plame case but prosecutor Patrick Fitzgerald believed she had information important to his investigation.

A federal judge ordered Ms. Miller to jail in July for contempt of court for refusing to testify in the leak investigation. Ms. Miller said she was upholding the journalistic principle of not revealing confidential sources. "I said to the court before I was jailed that I did not believe that I was above the law and that I would, therefore, have to go to jail because of my principles. But once I satisfied those principles, I was prepared to testify," she said.

The leak investigation also involves one of President Bush's top political advisers, Karl Rove, who reportedly has previously testified before the grand jury.