MILWAUKEE, Wisc. (AP) -

U.S. District Court Judge Rudolph Randa, whose rulings included the John Doe investigation into Gov. Scott Walker's campaign, has died at age 76.

Randa's secretary, Cary Biskupic, confirmed Randa's death following a battle with cancer that sent him into semi-retirement in February. Randa died early Monday. 

He was appointed to the federal bench in 1992 by President George H.W. Bush. Randa was born in Milwaukee and earned his law degree at the University of Wisconsin.

He served in the Army in Vietnam for two years, earning the Bronze Star. He worked in the Milwaukee city attorney's office and as a circuit court and state appeals court judge.

Randa's ruling in 2014 blocked a secret probe into the governor's campaign, a decision an appeals court eventually overturned and sent back to the Wisconsin courts.