Born in Plainfield, NJ and raised in Alexandria, VA, Fitzpatrick was recruited to Georgetown by coach Tom Nolan. At the Hilltop, Fitzpatrick joined fellow St. John's College HS teammate Brian Sheehan on a 1958-59 varsity team that returned only four players from the season before. Fitzpatrick, at just under 6-4, played center and power forward on an undersized team that finished 8-15. Hobbled by a knee injury over his final two seasons, Fitzpatrick averaged 4.2 points and 4.2 rebounds in an abbreviated 31 game career, graduating from the College in 1961.

After Georgetown, Fitzpatrick served in the military and followed with a 29 year career in the FBI before retiring to a new avocation: historian. Fitzpatrick spent over seven years writing a 761 page biography of Maj. Gen. Charles Barrett (1885-1943), a local war hero from Alexandria, who commanded the 3rd Marine Division in World War II. The circumstances of Gen. Barrett's death became a major subject of Fitzpatrick's extensive research.

"The Marine Corps was very sensitive about this because when he died in the Pacific in 1943, the war was in full swing," Fitzpatrick recounted in a 2003 article on the book. "There was great concern at the time that we didn't want the Japanese to find out that the top commander in the South Pacific had died and the circumstances surrounding his death. The Court of Inquiry that was called promptly ruled that his death was accidental, but those findings were classified until 1947. As a result, a lot of rumor surrounded the actual circumstances of his death, and that had never been cleared up in any substantive way. I set out to try and do that and have included the court report in my book."

Fitzpatrick penned a second book in 2010 on the life of four star Gen. Lemuel C. Shepherd, Jr. (1896-1990), who became the first Marine Commandant named to the Joint Chiefs of Staff. Fitzpatrick was also named a member of the Marine Corps Heritage Foundation.