The Dragnet radio show is a police crime drama series surrounding Joe Friday and his few partners he has throughout the show. Dragnet ran from June 1949 to February 1957, and later became a tv show, also now in the public domain. Dragnet was thought up by Jack Webb, who also starred as Joe Friday. Jack Webb when developing Dragnet wanted to focus on reality, giving the police officers no bs underplayed personalities.
Dragnet had 314 original episodes running from June 1949 to September 1955. Download all the episodes here at the source.