The investigation into the leak of covert CIA operative Valerie Plame Wilson is heating up. Evidence is mounting that senior officials in the office of Vice President Dick Cheney and the National Security Council conspired to unmask Plame Wilson's identity to reporters in an effort to stop her husband from publicly criticizing the administration's pre-war Iraq intelligence, according to sources close to the two-year-old probe.

In recent weeks, investigators working for Special Prosecutor Patrick Fitzgerald have narrowed their focus to a specific group of officials who played a direct role in pushing the White House to cite bogus documents claiming that Iraq attempted to purchase 500 tons of uranium from Niger, which Plame Wilson's husband, former Ambassador Joseph Wilson, had exposed as highly suspect.

One high level behind-the-scenes player who has been named by witnesses in the case as a possible source for reporters in the leak is Robert Joseph, formerly the director of nonproliferation at the National Security Council. Joseph is responsible for placing the infamous "sixteen words" about Iraq's attempt to purchase uranium from Niger in President Bush's January 2003 State of the Union address.

It's unknown when Fitzgerald will present the grand jury with additional evidence related to this aspect of the case or if he is close to securing indictments. The sources said the Special Prosecutor is very "methodical," and they expect the investigation to continue well into the spring.

The new grand jury hearing evidence in the leak case was empanelled in November. Right now, the jurors are still absorbing two years' worth of evidence Fitzgerald presented to the jurors a couple of weeks after the previous grand jury's term expired at the end of October. Sources said the jurors have raised numerous legal questions about unnamed senior Bush administration officials against whom Fitzgerald is trying to secure indictments.

Sources close to the probe said witnesses involved in the case told FBI investigators that Joseph was one of the recipients of a classified State Department memo in June 2003 that not only debunked the Niger allegations but also included a top-secret reference to Valerie Plame Wilson's work for the CIA, and that she may have been responsible for recommending that the CIA send her husband to Niger to investigate the uranium claims in February 2002.

Joseph did not return calls for comment. A spokeswoman for the vice president's office said she would not comment on "rumors" or "speculation" as long as the investigation is ongoing. Hadley's spokeswoman also did not return calls for comment, but she has said in the past that Hadley played no role in the leak.

The sources added that the witnesses testified that Joseph and then-Deputy National Security Adviser Stephen Hadley had worked directly with senior officials from vice president Cheney's office - including Cheney's former chief of staff, I. Lewis "Scooter" Libby, National Security Adviser John Hannah, and White House Deputy Chief of Staff Karl Rove - during the month of June to coordinate a response to reporters who had phoned the vice president's office and the NSC about the administration's use of the Niger documents.

Libby was indicted in October on five counts of lying to investigators, perjury, and obstruction of justice related to his role in the Plame Wilson leak. Legal scholars said that Fitzgerald can ask a grand jury to add conspiracy charges against Libby if he uncovers evidence that Libby and other administration officials worked together to leak Plame Wilson's identity to reporters in an effort to silence her husband. If additional charges were filed against Libby it would come in the form of a superseding indictment. Fitzgerald would have to introduce new evidence and witnesses against Libby to the grand jury, and the grand jury would decide whether there were enough evidence to support the superseding indictment.

In a court filing made public Friday in response to a defense motion in which Libby's attorneys wanted Fitzgerald to turn over highly classified documents to assist the defense's case, Fitzgerald made it clear that Libby was not charged with conspiracy.

"Libby is not charged with conspiracy or any other offense involving acting in concert with others, and the indictment lists no un-indicted co-conspirators," states Fitzgerald's motion, which asks a judge to deny the defense motion seeking evidence Fitzgerald said is unrelated to Libby's criminal indictment.

That could change, however, the sources said, if there is enough evidence to support conspiracy charges.

Although that remains to be seen, former State Department and CIA officials who have testified about their role in the leak said they believe officials at the National Security Council and in the vice president's office worked together to unmask Plame Wilson to reporters, specifically to undercut her husband's credibility. They said that Joseph was one NSC staffer who worked with Cheney officials to do so.

Joseph, who is now the Under Secretary of State for Arms Control - a position once held by John Bolton, now United States Ambassador to the United Nations - testified before the grand jury that he played no part in the leak and was not involved in attempts by the administration to discredit Wilson.

Moreover, Joseph testified that he did not recall receiving a warning in the form of a phone call from Alan Foley, director of the CIA's nonproliferation, intelligence and arms control center, saying that the "sixteen words" should not be included in Bush's speech, the sources said.

Foley had revealed this element during a closed-door hearing before the Senate Select Committee on Intelligence back in July 2003 - just two weeks after Wilson wrote an op-ed in the New York Times that proved the administration cited suspect intelligence claiming Iraq attempted to purchase uranium from Niger.

The Senate committee had held hearings during this time to try to find out how the administration came to rely on the Niger intelligence at a time when numerous intelligence agencies had warned top officials in the Bush administration that it was unreliable.

Foley said he spoke to Joseph a day or two before President Bush's January 28, 2003, State of the Union address and told Joseph that detailed references to Iraq and Niger should be excluded from Bush's speech. Foley told committee members that Joseph agreed to water down the language and would instead, he told Foley, attribute the intelligence to the British, which is exactly what Bush's speech said.

However, a few weeks before Foley's meeting with the Senate committee, the Niger intelligence was beginning to unravel and threatened to expose the roles of Libby, Hadley, Joseph, Hannah, and Rove in getting the administration to rely upon it to build the case for war.

The sources said it was during this time that Libby, Hadley, Joseph, Hannah and Rove plotted to silence Wilson by leaking his wife's name to a specific group of reporters, saying that she chose him for the fact-finding mission to Niger and as a result his investigation was highly suspect. It's unclear what role, if any, Cheney played, but the sources said Fitzgerald is trying to determine if the vice president was involved.

The sources said Hannah is one of the cooperating witnesses in the probe.

The sources said this time frame was chosen because there were "rumors" that Wilson was "going to go public" and reveal that he had checked out the Niger claims on behalf of the CIA and that there was no truth to them. According to the sources close to the probe, all five of the officials have spoken with reporters about Plame Wilson.

At the same time that Plame Wilson's CIA status was leaked to reporters, Libby, Rove and Hadley had been exchanging emails that included draft statements explaining how the "sixteen words" ended up in President Bush's State of the Union address, the sources added.

"Before Mr. Wilson's article appeared in the New York Times," one source close to the case said, "the administration still insisted that Niger still had merit. It was only after the article had been published that the White House accepted responsibility."

Wilson disclosed in an op-ed he wrote in the New York Times that he had been the special envoy chosen by the CIA in February 2002 to travel to Niger to investigate allegations that Iraq tried to purchase 500 tons of yellowcake uranium from the African country.

Wilson's fact-finding mission had come as a result of additional questions Vice President Cheney raised with the CIA about the veracity of those allegations a month or so before Wilson was selected for the mission. Wilson wrote in the column that he had reported back to the CIA eight days after his trip that there was no truth to the charges. In his column, he accused the administration of ignoring his report. He said President Bush and Cheney continued to cite the Niger uranium intelligence, knowing it was false, in order to dupe the public and Congress into supporting the war.

In the four months prior to writing his column, Cheney and officials from the NSC insisted that the Niger intelligence had merit, and said as much publicly, despite the fact that the International Atomic Energy Association found that they were crude forgeries. Moreover, there is evidence that Cheney, Hadley, Libby, and numerous other officials were warned as early as March 2002 - one year before the start of the Iraq war - that claims suggesting Iraq tried to purchase uranium from Niger were baseless.

Indeed, witnesses in the case have testified that President Bush's senior aides, the vice president's office, the Pentagon, the Defense Intelligence Agency, the State Department, the Joint Chiefs of Staff, the Justice Department, the FBI, and the National Security Council had received and read a March 9, 2002, cable sent by the CIA that debunked the Niger claims.

The cable was prepared by a CIA analyst and was based on Wilson's oral report upon his return from Niger. It did not mention Wilson by name, but quoted a "CIA source" and Niger officials Wilson had questioned during his eight-day mission, who said there was absolutely no truth to the claims that Iraq had tried to purchase 500 tons of yellowcake uranium ore from Niger.

Cheney and other officials connected to the leak have said over the years that they never saw such a report from the CIA, and had never heard of Wilson until he became the subject of news accounts in which the former ambassador called into question the veracity of the Niger documents upon which the uranium claims were based.

The sources said it was during this month, March 2003, when Wilson arrived on the administration's radar as a result of his public comments that alleged the White House had manipulated intelligence, that Cheney, Libby, and Hadley spearheaded an effort to discredit Wilson.

It was during the course of their attempts to attack Wilson's credibility and rebut his charges that officials in the State Department, the CIA, Cheney's office, and the National Security Council - many of whom were responsible for pushing the administration to cite the Niger claims - learned that Wilson's wife was a covert CIA agent and, upon learning that she may have been responsible for sending Wilson to Niger, leaked her name to a handful of reporters.

Five days after Wilson's explosive column was published, CIA Director George Tenet accepted responsibility for allowing the infamous "sixteen words" to be included in Bush's January 28, 2003, State of the Union address. Many people interpreted this as Tenet falling on his sword to protect the president.

Two weeks later, the CIA revealed that other administration officials were culpable as well. CIA officials sent Hadley two memos in October 2002 warning him not to continue peddling the Niger claims to the White House because the intelligence was not accurate.

Hadley, who didn't heed the CIA's warnings at the time, said during a press conference on July 23, 2003, that he had forgotten about the memos.

Jason Leopold is the author of the forthcoming book NEWS JUNKIE, to be published in April. Visit for a preview. This article first appeared on TruthOut