What was the first police detective television aired?

Martin Kane, Private Eye. It was the first detective show ever aired, appearing in 1949. Starring William Gargan, it was sponsored by the United States Tobacco Company. Everyone hung out at a tobacco shop run by a character named Happy McKann, played by Walter Kinsella. The plotlines, and of course the commercials, were heavily tobacco oriented.

I'd like to point that Martin Kane was a private, not a police detective, but it is the first detective show aired.