With the smash success of Dragnet, many networks and producers began to play follow the leader. On NBC, Dragnet was followed up with Tales of the Texas Rangers which dramatized real-life tales from the Texas Rangers. CBS countered with The Line Up and later 21st Precinct,  and then Nightwatch which while following an actual policeman in the field was as realistic as it got in a show that was pre-cursor to modern police reality dramas like Cops.

The Line Up was a hard-boiled drama of police action. Like Dragnet, it realistically showed police doing their jobs. Unlike Dragnet, it was not based on “cases taken from police files.” Rather The Line Up made its fictional cases seem realistic, from kidnappings and murders to thefts and obscene phone calls.  The Line Up radio show was not set in any particular city. However, when the series moved to television, it was set in San Francisco.

The series starred William Johnston as Lieutenant Ben Guthrie and began with Wally Maher playing the role of Sergeant Matt Grebb. After Maher's passing in 1951,  Jack Moyles took over the supporting role as Sergeant Pete Karger.

The Line Up, as the title indicates, centered around the police line up. The show always began with one. The Sergeant in charge of line would say, “May I have your attention please? You people  on the other side of the wire in the audience room, may I have your attention please.” He would then give his name and say, “I’ll explain the line up to you. Each of the suspects you will see will be numbered.  I’ll call out their number, their name, and charge.  If you have any questions or identifications, please remember the number assigned to the prisoner as I call his name. At the end of each line when I ask for questions or identifications, call out the number.  If you’re sure or not too sure of the suspect, have him held.   The officers who took your name will assist you, they’re seated among you. Please be prompt with your questions or identifications. When the prisoners leave here,  they are sent to the washroom and dressed back into their jail clothes. It makes it quite difficult to bring them back after they leave here. The questions I ask these suspects are merely to get a natural tone of voice so do not pay too much attention to their answers as they often lie. Bring on the line.

”While the line up was rarely the key to solving the case, it did give the show a rhythm and it also allowed for humor in the interrogation of the suspects by the sergeant. The series began as a Summer Replacement for The FBI in Peace and War in 1950, but quickly got its own time slot and would remain on radio until the Spring of 1953 before becoming TV only.