Now Chicago's top federal prosecutor takes his reputation as a tough, aggressive crime buster to Washington and the politically sensitive job of trying to find out who leaked the name of a CIA operative to a columnist.
Those who know him say the 43-year-old transplanted New Yorker and avowed political independent has the right temperament for the job.
"Elliot Ness with a Harvard law degree and a sense of humor," James Comey, the Justice Department's No. 2 official, told reporters Tuesday after announcing that Attorney General John Ashcroft was recusing himself from the investigation.
Investigators want to know who leaked the name of Valerie Plame, an undercover CIA (search) operative, to syndicated columnist Robert Novak last July. Fitzgerald is to head the investigation and report to Comey, a longtime friend who worked alongside Fitzgerald when both were assistant U.S. attorneys in New York.
In a statement Tuesday, Fitzgerald said he would begin his work immediately but declined to comment further.
"He has been given a very difficult assignment," said U.S. Sen. Dick Durbin, D-Ill. "Very few of these investigations lead to anything, but I have no doubt that he will handle it professionally."
Thomas J. Kneir, special agent in charge of the Chicago office of the FBI, who has worked beside Fitzgerald on politically explosive investigations for the last two years, praised Fitzgerald's ability.
"If given free rein to do what needs to be done, I'll put my money on Pat to accomplish the mission he's been tasked with," Kneir said.
Fitzgerald is the son of an Irish immigrant father who worked as an apartment house doorman in Brooklyn. A bright student, he graduated Phi Beta Kappa from Amherst College and received a Harvard law degree in 1985.
He worked briefly for a private law firm in New York and then joined the U.S. attorney's office for the Southern District of New York.
Ten years after getting his law degree, Fitzgerald was named chief of the organized crime-terrorism unit and began investigating terrorism. He made his name with the prosecution of 12 alleged terrorists for a conspiracy that included the 1993 bombing of the World Trade Center. He also prosecuted four people charged in 1998 bombings of two U.S. embassies in Africa. All got life in prison.
In September 2001, he became U.S. attorney in Chicago on the recommendation of U.S. Sen. Peter Fitzgerald, R-Ill., who is no relation. The senator said he had asked then-FBI Director Louis Freeh for the name of someone who from outside Chicago who would be fully independent.
Fitzgerald immediately set a tough, aggressive tone. He told reporters he would bring charges even if there was no assurance of a conviction.
"As long as we know that we're right," he said.
A sweeping investigation of corruption under former Illinois Gov. George Ryan was already under way when Fitzgerald arrived, but he pushed it along. Ryan's campaign manager and close political allies have been prosecuted under Fitzgerald, and the 69-year-old former governor was charged with racketeering this month.
Fitzgerald also personally prosecuted Islamic charity director Enaam Arnaout, whom he accused of quietly funneling aid to Al Qaeda terrorists. Arnaout never admitted links to Al Qaeda but pleaded guilty to defrauding donors to his Chicago-based charity. He is serving more than 11 years.
Chicago defense lawyers praise Fitzgerald as a highly skilled and energetic prosecutor but note his distaste for compromise.
Prominent defense attorney Jeffrey Cole said he recently wrote to Fitzgerald to request a sit-down involving a client who is under investigation. Nothing doing.
"It wasn't that he was unwilling to meet with me, but he just felt there was no point because the decision had been made," Cole said. "He doesn't give anybody a break in a criminal case."