He leaves behind a legacy of prosecuting political corruption in Illinois, including the convictions of governors George Ryan and Rod Blagojevich.
"I don't know what I'm going to do next but public service is in my blood. If the phone rings, I will answer that phone," Fitzgerald said.
"I think it's healthy at a certain point that there be change at the top," the prosecutor continued, "and I put that on me to sort that out and in my mind both a desire to sort out whatever I do next, and for the office to have change, I thought this was the right time."
Fitzgerald said he wants to take the summer to decompress - to be with his wife and young sons - after having established a reputation as a workaholic prosecutor.
For now, he said he doesn't know what he'll do next. There is one thing, though, he'll rule out.
"I'm not wired to campaign for anything or run for elective office period," he said.
That is not meant, he said, to besmirch those who do run for office. It's just not his thing.
He was asked whether he has regrets over decisions made, or not made. The answer, of course, is yes without listing them. But there's clearly one remark Pat Fitzgerald would like to take back.
"The conduct would make Lincoln roll over in his grave," Fitzgerald said in 2008.
That comment the day of the Rod Blagojevich indictment brought a flood of criticism for a straight arrow prosecutor who in public comment seldom left what was specifically laid out in the indictment.
"If you're asking me if I regret that, it seemed like a good idea at the time which tells you in all seriousness, I probably could have had a colder shower, a little more sleep and some decaf," he said Thursday.
But, no apologies for an investigation that Fitzgerald says stopped serious crimes in progress.
And what of his successor? The man who came here as the outsider, to the chagrin of many, says zip code doesn't matter, but independence does. And so too does reliance on the team that does the legwork.
"So to the folks I work with, if I had one year with as US Attorney in the district of Northern Illinois with that team I'm so blessed, I'd use words like dream, treasure, gift, and having had a decade, I can't put into words what that means to me," Fitzgerald said.
At news conferences over the past 11 years, he has always stood with police and prosecutors behind him. On Thursday, for 35 minutes, he stood alone -- a picture he says he was not entirely comfortable with.
And it might also be said that he's not comfortable with the never-ending battle against public corruption, despite an abundance of high profile convictions. He said good progress has been made, but there've also been frustrating setbacks, in large part because of a culture here that for years has tolerated corruption.