Milner had a one-year bout with polio as as a child.
Milner attended the University of Southern California.
Milner and "Adam-12" (1968) co-star Kent McCord were reunited in a Nashville Beat (1990) (TV) on the Nashville Network. McCord played an L.A. cop visiting his friend Milner, an ex-L.A. cop who became a Nashville cop.
While stationed at Ft. Ord, California, during his army hitch in the early 1950s, Milner's army buddies included pre-stardom David Janssen and Clint Eastwood.