Mr. District Attorney was a popular radio crime drama which aired on NBC and ABC from 1939 to 1952. It also had a brief run on television. In the radio version, the lead character's name was never stated.
Dell Four Color #13 presented several tales of the D. A. in 1942, all fairly short. Here is one of them, with art by Maurice Kashuba. (These were actually collected from Dell's earlier THE FUNNIES)
As usual, click on the pages for full size..they are fairly large scans.