More than a decade before Family Affair made him a major TV star, Brian Keith made his debut in the crime drama, Crusader, which lasted 52 episodes between 1955-7.
Keith played journalist Matt Anders, a freelancer whose millieu went beyond investigative reporting.
Edit: 4/1/15: The video previously posted was deleted when the poster's account was terminated by YouTube. Instead, we have a sample intro:
Revue (now NBC-Universal) churned out crime dramas like they were on an assembly line. The angle of using an investigative reporter was just a variant on the usual procedurals of the period. Believe it or else, before I ran across the above video, I wasn't even aware of this series, and assumed that Keith's debut series was the Four Star oater, The Westerner, which we will cover at a later date.