From 1949 to 1957, Dragnet pioneered new levels of realism on radio. Every crime investigated by Sergeant Joe Friday was taken from the actual case files of the Los Angeles Police Department, with only "the names changed to protect the innocent". There were multi-layered sound effects; the actors used accurate police lingo, abbreviations, and penal codes; and the show didn't shy away from stories about heinous crimes or stories that had unhappy endings. Created and produced by Jack Webb, Dragnet was much more than "just the facts".
One thing I have noticed with the Dragnet series is there is an underlying story. If you listen to them out of order (the aired dates) you may be confused at some of the family issues, partner names, and the like. I still like, them out of order or in order, it really doesn't matter. I just laugh when I get one of those ah-hah moments.