Colleagues say Fitzgerald – 'Fitzy' to his friends – has little room for a social life and indeed he married only this year at the age of 47, to a teacher Jennifer Letzkus.
His internet blog, which is subtitled 'Fighting for Truth, Justice and the American Way', reveals there was no time for a honeymoon.
Fitzgerald's work ethic was inherited from his father, an Irish immigrant who worked as a doorman in Manhattan and never took a holiday as he raised a family of four in Brooklyn, New York.
Attending the Jesuit, Regis High School and growing up in a strict but loving working class household also gave him a strong sense of right and wrong, friends say, that he has carried into his professional life and has made him genuinely indignant at wrongdoing.
There was an element of the crusader at his press conference, when he spoke about how the culture of corruption in Illinois could be beaten.