WASHINGTON (CNN) -- Deputy Attorney General Paul McNulty, the No. 2 official at the Justice Department, has resigned, Attorney General Alberto Gonzales announced Monday.

McNulty cited personal reasons for his resignation, which he said will be effective at an unspecified date in late summer.

"The financial realities of college-age children and two decades of public service lead me to a long overdue transition in my career," he wrote. (Read McNulty's resignation letter [PDF])

His resignation comes amid a controversy over the department's firing of eight U.S. attorneys last year, a move that has sparked a firestorm on Capitol Hill. He was one of the key figures in meetings and discussions about the shakeup, and investigators from the House and Senate Judiciary committees grilled him for more than eight hours in April.

In a statement announcing McNulty's resignation, Gonzales praised him as "an effective manager of day-to-day operations" since he took office in November 2005.

"Paul is an outstanding public servant and a fine attorney who has been valued here at the department, by me and so many others, as both a colleague and a friend," Gonzales said. "He will be missed. On behalf of the department, I wish him well in his future endeavors."

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