While holding down the job of U.S. attorney in Chicago, Fitzgerald commuted to the nation's capital, investigating the disclosure of the identity of CIA operative Valerie Plame all the way to the office of Vice President Dick Cheney.
"We're all going back to our day jobs," Fitzgerald said last year at the U.S. courthouse in Washington after winning a conviction against Cheney's former chief of staff.
Since then, Fitzgerald's "day job" in Chicago has been incredibly busy.
On Tuesday, Fitzgerald shook the Illinois political world with the arrest of Blagojevich, a Democrat, for allegedly conspiring to sell the U.S. Senate seat left vacant by President-elect Barack Obama.
It's unusual for a federal prosecutor to have on his resume two such politically sensitive investigations in different parts of the country. And that's not all. In an extraordinarily productive seven-year tenure, Fitzgerald also won the conviction of the previous Illinois governor, Republican George Ryan, who is in prison for racketeering.
All of which raises the question: What's next for the 47-year-old Fitzgerald?
Ordinarily, an incoming president chooses new U.S. attorneys, but Obama has pledged to keep Fitzgerald on the job, so the latest corruption case is not likely to be Fitzgerald's swan song.
"I think he has been aggressive in putting the city on notice and the state on notice that he takes issues of public corruption seriously," Obama told the Chicago Tribune in March.
Fitzgerald was appointed by a Republican president, George W. Bush, but Illinois Democratic Sen. Dick Durbin said last week he will recommend another term for the prosecutor if he wants to stay.
Like U.S. district judgeships, the job of U.S. attorney most often goes to the person recommended by the senior senator of the president's party -- Durbin, in the case of the incoming president.
Fitzgerald's original political patron was Republican Illinois Sen. Peter Fitzgerald, no relation, who did not run for re-election in 2004.
In the Blagojevich case, Fitzgerald realized he couldn't wait until all leads had been run down.
"Think of the mess there would be if they waited for the sale of a Senate seat to go through," said Peter Zeidenberg, who worked alongside Fitzgerald while investigating the Plame leak. "Then what do you do with the senator? Does he get impeached?"
Critics often call Fitzgerald a zealot. Fitzgerald doesn't back away from that but says there's a difference between being zealous and being overzealous.
"Do I have zeal? Yes. I don't pretend I don't," Fitzgerald said in 2005. "As a prosecutor, you have two roles: Show judgment as to what to go after and how to go after it. But also, once you do that, to be zealous. And if you're not zealous, you shouldn't have the job. Now sometimes 'zealous' becomes a code word for overzealous and I don't want to be overzealous. I hope I'm not."
Born in Brooklyn, N.Y., the son of a Manhattan doorman, Fitzgerald spent years in the legal trenches advancing his career one criminal case at a time.
Fitzgerald served 13 years as an assistant U.S. attorney in the southern district of Manhattan, helping prosecute organized crime cases as well as terrorism cases involving the 1993 bombing of the World Trade Center and the 1998 bombings of U.S. embassies in Kenya and Tanzania.
For the embassy bombings trial, Fitzgerald taught himself some basic Arabic. Often, he would question an Arabic-speaking witness using an Arabic word or two, spelling it for the court reporter, and translating for the jury.
During his investigation of the leak of Plame's identity as a CIA official, Fitzgerald took his share of criticism, especially from conservative Republicans who objected to his prosecution of Cheney's former chief of staff, I. Lewis "Scooter" Libby. Libby was never charged with leaking that Plame was employed by the CIA, but rather with lying to the FBI and to a federal grand jury about his role in the leak.
Fitzgerald ignored his critics but spoke out when Bush commuted Libby's 30-month prison sentence as excessive.
Abandoning the politically cautious path of remaining silent, Fitzgerald disputed Bush's assertion by saying Libby was sentenced under the same laws as other criminals.
In court, Fitzgerald is renowned for his mastery of minutiae, for thinking quickly on his feet and being an exhaustive cross-examiner. But he shuns the polished look of white-shoe attorneys. He has an "aw shucks" demeanor that friends say is not an act.
During the Libby trial, he once pressed a very precise matter of law that sent the judge for his law books.
"I'm sorry to be a geek about this," he said.