[1] Broadcast from the studios of WJZ in Newark, New Jersey, the series premiered on the ABC Radio Network on Monday, January 21, 1946, at 8:30 p.m.,[2] as part of a block of four new programs (I Deal in Crime, Forever Tops, and Jimmy Gleason's Diner) and ran until 1951.
O'Hara, and the supporting cast included Betty Garde, Paul Stewart, Linda Watkins, Mary Patton as Lila North and Vicki Vola, who was also the female lead in Mr. District Attorney.
The success of the radio series led to a movie, The Fat Man (1951), directed by William Castle with a flashback-within-a-flashback storyline.
Smart retained his role as detective Brad Runyon, investigating the murder of a Los Angeles dentist with an assist from Bill Norton (Clinton Sundberg).
One of the suspects is portrayed by famed Barnum & Bailey clown Emmett Kelly in his screen debut as an actor.