The White House official who first identified the CIA officer at the heart of a yearslong leak investigation may have been Vice President Dick Cheney (search), sources close to the probe said.

Cheney's chief of staff, I. Lewis Libby (search), discussed Valerie Plame (search) with reporters and could be facing indictment as a special prosecutor's 22-month-long investigation nears its conclusion. But as first reported by the New York Times, notes of a conversation between Libby and his boss a month before Plame's name was made public indicate Libby learned about the CIA officer during a conversation with the vice president.

The Times reported its sources were lawyers involved in the case. A separate source confirmed their account to FOX News.

White House spokesman Scott McClellan on Tuesday repeated a phrase that's become very familiar to reporters, telling them he would not comment on "the investigation while it's ongoing."

It would not likely have been a crime for Cheney and Libby to have discussed Plame, since both presumably possessed security clearances. But the revelation of the conversation, which was likely already well known by Special Counsel Patrick J. Fitzgerald (search) and comes mere days before possible criminal charges are expected, raises more questions than it answers.

Among them: For what purpose did Cheney disclose Plame's identity to Libby? Was Cheney aware Libby apparently then discussed Plame with Karl Rove (search), President Bush's deputy chief of staff, and that both were talking about her with reporters? Did Cheney speak to reporters about Plame himself?

Not all the sources in this case are known to the public. One of syndicated columnist Robert Novak's (search) sources is a mystery, as is the identity of the person who discussed Plame with Walter Pincus (search) of the Washington Post. New York Times reporter Judith Miller (search) said she "could not recall" who gave her Plame's name, which she misspelled as "Valerie Flame" in a notebook.

The new development could mean Libby is at risk of perjury or obstruction charges, since it has been widely reported that he told a grand jury that he initially learned Plame's identity during conversations with journalists.

The White House has been bracing itself for the end of Fitzgerald's probe, expected on Friday when the grand jury's term expires. Both Rove and Libby have been informed that they could face indictment.

Fitzgerald, a U.S. prosecutor in Chicago, has been tasked with determining whether Plame's identity was leaked in order to discredit her husband, former Amb. Joseph C. Wilson. Wilson had traveled to Niger in a CIA-sponsored trip to check out allegations that Iraqi officials sought to purchase nuclear weapons materials there. Wilson wrote up his findings in a Times op-ed titled "What I Didn't Find in Africa."

Wilson's report that the Iraq-Niger connection was dubious at best led to an embarrassing episode for Bush: the White House's retraction of 16 words in the 2003 State of the Union speech that were used to support the administration's decision to invade Iraq.

Wilson was reportedly on the administration's radar as a potential troublemaker before Novak identified his wife, Plame, on July 14, 2003. According to Tuesday's Times report, Cheney learned Plame's identity in a conversation about her husband with then-CIA Director George Tenet.

Wilson has been the subject of criticism himself. Libby and Rove apparently discussed Plame with reporters to wave them off Wilson's hints that Cheney's office had anything to do with his Niger trip. Defenders of the administration have said that Plame arranged her husband's trip, suggesting cronyism, but reports indicate she merely suggested him as qualified for the task.

Tuesday's reports are the first indications that the vice president discussed Plame with aides. Since Fitzgerald last interviewed Cheney more than a year ago, the revelations could indicate that discrepancies between Cheney and Libby's testimony have surfaced.

The contents of the memo also raise questions about a September 2003 Sunday talk show interview Cheney gave, in which he denied knowing Wilson and had "no idea who hired him."

The Times reported that Cheney last gave testimony under oath a year ago. It is not yet known if he acknowledged speaking to Libby about Wilson's wife.

McClellan dismissed the notion that Cheney was dishonest about his role in the leak.

"I think it's a ridiculous question," he said. "The vice president, like the president, is a straightforward, plainspoken person."

Before Tuesday, the only thing known about Libby's dealings with the grand jury was that he testified he first learned Plame's identity from other reporters. Most of the heat in this case had been on Rove, Bush's longtime adviser, who also discussed Plame with journalists.

"I don't know whether it's a good day to be Karl Rove, but it's certainly taking the spotlight off him," said Michael Greenberger (search), director of the Center for Health and Homeland Security at the University of Maryland.

"I still think Rove may have problems in things he told the grand jury that were inconsistent with later stories he told them. I certainly don't think he will rest easy until he hears he's not indicted."

Greenberger said the last-minute revelation about Cheney might be an indication Fitzgerald has the case wrapped up.

"Maybe there is some attempt going on now, if Libby is indicted, to turn him against the vice president," Greenberger said. "It appears what Fitzgerald has been trying to find out is whether Cheney set in motion an operation to try to leak the name of Valerie Plame."

For several months, sources within the investigation have been telling reporters that it was unlikely anyone would be charged with violating a 1982 act that made it illegal to intentionally blow a covert U.S. agent's cover. Plame's undercover status has been the subject of debate, and testimony indicates there is little to prove Rove or Libby knew her identity was a secret.

But Fitzgerald has reportedly been mulling other charges, possibly obstruction of justice in an investigation and conspiracy. That he is apparently waiting until the 11th hour to announce his findings has been the source of great tension and speculation in the Beltway.

A former federal prosecutor who investigated national security matters for nearly three decades said Fitzgerald is just doing his duty by keeping details of the investigation top-secret.

"The press has really been driving this story," said John L. Martin, now a consultant.

"I don't know if we're seeing a tenth of the picture or half of it or even the whole picture. We just aren't even in a position to assess that," Martin said of media speculation.

If Rove or Libby is indicted on anything, it is likely either or both would resign.

While sitting presidents cannot be indicted, charges may be brought against sitting vice presidents.

FOX News' Carl Cameron contributed to this report.