Novak's article appeared about a week after the agent's husband, former Ambassador Joseph Wilson IV (pictured below), publicly challenged President Bush's claim in his State of the Union address that Iraq had tried to buy uranium from the African nation of Niger.

In an op-ed piece published July 6 in The New York Times, Wilson said the CIA had sent him to Niger in 2002 to look into the intelligence claim, but found no substantial evidence to support the president's allegation. Wilson charged that the Bush administration "twisted" some of the intelligence "to exaggerate the Iraqi threat" and to justify an invasion of Iraq.

Wilson's article and his subsequent public statements set off a firestorm of criticism over the president's rationale for going to war with Iraq. The Bush administration later recanted the uranium "yellow cake" claim after learning the information was based at least in part on forged documents.

This claim was later found to be essentially accurate after all, according to results of British and American intelligence reviews. Britain's Butler Committee report, released in July 2004, called the Iraq-Niger uranium allegation "well founded," and the U.S. Senate Intelligence Committee determined there was "a number of intelligence reports" confirming that Iraq was actively trying to purchase uranium from several African nations.

Novak's July 14 column, entitled "Mission to Niger," downplayed Wilson's account, asserting the CIA regarded Wilson's finding in Niger as "less than definitive." Then, Novak, citing "two administration officials," wrote that the CIA had sent Wilson to Niger at the suggestion of his wife, Valerie Plame, an "agency operative on weapons of mass destruction."

Wilson later accused the "two senior administration officials," whom Novak has never identified publicly, of trying to undercut Wilson's credibility because of his charges against the Bush administration.

The intentional, unauthorized disclosure of a covert operative's identity is a violation of a 1982 federal law, the Intelligence Protection Act, which imposes maximum penalties of 10 years in prison and $50,000 in fines.

The two senior administration officials had reportedly called at least six journalists based in Washington, D.C. to disclose Wilson's wife's identity, but those journalists did not use the leaked information because they did not want to name an undercover agent or because they did not find the information relevant to Wilson's Niger finding, according to a Washington Post article on Sept. 28, 2003.

Indeed, Time magazine on July 17, 2003 published an article, entitled "A War on Wilson?" by Matthew Cooper, Massimo Calabresi and John Dickerson, examining how administration officials were taking "public and private whacks at Wilson" since the former ambassador penned his op-ed for The New York Times. In this context, the reporters noted that the magazine had received a leak of Plame's identity:

"And some government officials have noted to Time in interviews, (as well as to syndicated columnist Robert Novak) that Wilson's wife, Valerie Plame, is a CIA official who monitors the proliferation of weapons of mass destruction. These officials have suggested that she was involved in her husband's being dispatched Niger," the Time article stated.

At the same time, Time reported, government officials were "privately disputing the genesis of Wilson's trip" and if Plame was ever involved in the decision to send her husband to Niger.

About 10 days after Novak's column appeared, several Democrats in the Senate, among others, began urging the FBI to investigate the leak of Plame's identity. In a letter to FBI chief Robert Mueller dated July 24, Sen. Charles Schumer, D-N.Y., wrote that the disclosure has "possibly endangered Ms. Plame and her entire network of intelligence contacts."

The next day, FBI spokeswoman Susan Whitson said the agency would "look at the issue and make determinations about whether there is an investigation that is warranted."

Underscoring the severity of the leak, then-CIA Director George Tenet in late July prompted the Justice Department to look into the potentially illegal leak and the CIA filed a "crime report" with the Justice Department, pointing to a "possible violation of federal criminal law involving the unauthorized disclosure of classified information," The Washington Post reported on Sept. 28 and 30, 2003.

By late that September, Attorney General John Ashcroft announced the Justice Department would launch a preliminary inquiry, but the DOJ, not the FBI, would lead the investigation.

Almost immediately, several Democrats in the Senate called for the creation of a special counsel to head the investigation, saying that the attorney general could not impartially lead an investigation that focused in part on his colleagues at the White House.

In letters sent to Ashcroft and President Bush, Minority Leader Tom Daschle of South Dakota and three other senators said: "We do not believe that this investigation of senior Bush administration officials, possibly including high-level White House staff, can be conducted by the Justice Department because of the obvious and inherent conflicts of interests involved."

On Dec. 30, 2003, Ashcroft recused himself from any involvement in the inquiry, turning the reigns over to Deputy Attorney General James Comey Jr. Subsequently, Comey appointed a special investigator, Patrick Fitzgerald, the U.S. attorney in Chicago, to lead the probe and track down how the classified information was leaked.

The investigation into the leaking of Plame's name has resulted in a number of subpoenas and the prosecution has conducted numerous interviews, including with President Bush, Vice President Dick Cheney and the vice president's staff. Because the case is a federal grand jury investigation, the names of those who have received subpoenas or submitted to interviews are not public record.

-- Compiled by Liz Harper for the Online NewsHour