Libby's letter, which mentioned her vacations out West and urged her to "come back to life," also al

On her second day as a prosecution witness in Libby's perjury trial, Miller told the jury she believed Vice President Cheney's former chief of staff was the first person to tell her in the summer of 2003 that Plame worked at the CIA and was married to a critic of Bush administration Iraq policies. But she acknowledged: "I can't be absolutely absolutely certain."

Under cross-examination from one of Libby's lawyers intended to expose holes in her memory, Miller said that at least one of her reporter's notebooks contained Plame's initials and last name, although she mistakenly wrote it down as "Flame." Asked whether those notes came from conversations Miller has testified she had with Libby about the CIA officer, she replied, "I don't believe they came from Mr. Libby."

Pressed to reveal other sources who told her about Plame and her husband, war critic and former ambassador Joseph C. Wilson IV, Miller said: "I've searched my memory, and I just can't remember specific discussions with people about her."

The cross-examination by defense attorney William H. Jeffress Jr. attempted to blunt the potential damage to Libby from Miller's testimony yesterday. She recounted one meeting in Libby's White House office, another over breakfast at a downtown Washington hotel and a subsequent telephone call during which she said Libby revealed Plame's identity to her.

Her testimony is significant, because both meetings took place before the date Libby has told investigators he first learned of the undercover CIA officer from another journalist.

Libby is the only person charged as a result of a federal investigation into how Plame's name was disclosed to syndicated columnist Robert D. Novak, who first published it on July 14, 2003, and other journalists, in what prosecutors have alleged was an effort to discredit Wilson. Wilson, sent by the CIA to Africa to investigate reports that Iraq was attempting to acquire nuclear material there, had publicly accused the administration of twisting his findings.

The vice president's former top aide is not charged with the leak itself. He faces five felony counts alleging that he lied to FBI agents and a grand jury about his role in the disclosure. He has pleaded not guilty to all counts, contending that he forgot some of his conversations with reporters as he dealt with critical national security matters.

Miller's testimony this morning came after U.S. District Judge Reggie B. Walton resolved a dispute with First Amendment overtones between the defense and prosecution. It focused on how extensively Libby's lawyers should be allowed to explore Miller's memory by asking her to identify other sources with whom she discussed an op-ed article Wilson wrote a few months after the Iraq war began.

In that piece in the New York Times, Wilson described his CIA-sponsored mission to Africa in 2002, concluding that reports of Iraq's efforts to purchase uranium from Niger were unfounded.

Miller, who spent 85 days in jail in 2005 in an effort to avoid testifying, ultimately agreed to cooperate with Special Counsel Patrick J. Fitzgerald's investigation only after the prosecutor promised to confine his questions to her discussions with Libby.

This morning, Walton ruled that the defense could ask Miller only about sources with whom she spoke about Wilson or Plame, but not about the larger issues raised in Wilson's article. The judge said that broader question "goes far afield and would take us into an area that I don't think is in any way relevant to this case."

Walton also said he has reviewed Miller's notes in chambers and found no indication that other identifiable sources spoke to her about Plame. He said he would review the notes once more, and he suggested Miller remain available during the trial in case additional testimony from her is required.

After the ruling, Jeffress promptly asked Miller about conversations she had with "senior government officials and not-so-senior government officials" -- a reference to a statement Miller made during a television interview about the case. Miller, sounding frustrated, told the defense attorney that, in that interview, "I didn't say I remembered their names. I don't know what you want me to say. . . . I can't remember who I talked with."

After the cross-examination, Fitzgerald sought to minimize the notion that Libby might not have been Miller's original source. He asked her whether her notes with Plame's initials and misspelled last name were later in her notebook than notes from her meeting with Libby. She said that they were.

Also this morning, Fitzgerald said he plans to introduce a letter Libby wrote to Miller while she was in jail. Fitzgerald said the letter was important because it would show that Libby felt that Miller's full and truthful account could put him in legal jeopardy.

The prosecutor said Libby, after calling Miller to urge her to testify, wrote a letter that tried to encourage her to give specific testimony and leave out information that would be damaging to him. Libby's letter, which mentioned her vacations out West and urged her to "come back to life," also alerted her that all other reporters so far had told investigators that they already knew about Valerie Plame before talking to him or the topic hadn't come up in their conversations.

"He followed up the call with a letter saying 'here's why it's OK to testify and here's what others are saying,' " Fitzgerald told the judge. Fitzgerald said it was very important "that he would imply what he wanted her to say."

Walton said he didn't think the letter was relevant to Miller's testimony but might well be relevant to Libby's state of mind if he testifies.

Libby's attorneys had suggested to the judge that they plan to call him to the stand, but prosecutors believe they may try to avoid that if they think their case is going well.