In two years of dogged investigation, he has done what the media and the Democratic Party have shied away from and unpicked a plethora of inconsistencies, distortions and apparent out-and-out lies as the administration tries to justify the war in Iraq.
Yesterday's indictment of Scooter Libby, the first of a serving White House official in 130 years, on charges of obstruction of justice and lying to investigators and a grand jury related first and foremost to the revelation of a CIA agent's identity. Valerie Plame Wilson's cover was blown apparently as revenge on her husband, diplomat Joe Wilson, who went to Niger to investigate reports Saddam Hussein was buying uranium yellowcake and concluded - to the frustration of the administration - that the reports were bogus.
But the bigger picture, which Mr Fitzgerald may be only beginning to unveil, concerns the possibility that the US government deliberately concocted part of its case for war and misled Congress on the basis of information it knew was untrue.
It has been an astonishing investigation, in which senior White House officials from the President on down have been forced to retract, tone down or massage statements which turned out, as Mr Fitzgerald's work progressed, to be untenable.
The scandal has threatened the reputation of the New York Times, whose investigative reporter Judith Miller not only provided an echo chamber for the administration's unfounded allegations about Iraqi weapons of mass destruction but also - according to the paper's own findings - lied to her colleagues and appeared to be more interested in protecting her government sources, including Mr Libby, than defending the integrity of her trade.
Ms Miller spent 85 days in jail, ostensibly to avoid discussing conversations with Mr Libby even though he issued a waiver releasing her from her obligation of confidentiality.
Over and above the actions that have led to criminal charges the scandal has thrust one Bush administration official after another into spotlight.
President Bush himself was forced to back down after saying he would fire anyone found to be involved in the leak. Mr Cheney told an interviewer in 2003 that he had "no idea" who sent Joe Wilson to Niger. According to the indictment, however, it was Mr Cheney who first suggested that Mr Wilson be sent.
White House spokesman Scott McLellan stated "categorically" in October 2003 that Mr Libby and Karl Rove, President Bush's political strategist, were not involved in leaking Ms Wilson's name. He has since pleaded that he was merely passing on the assurances of others, and did not knowingly lie.
Mr Rove himself said at the time he had no knowledge of the Wilson leak - something that now appears untrue. Although he escaped indictment yesterday, Mr Rove remains under close investigation.
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