The original characters were created by Jack Boyle, who first published a short story in “The American Magazine” in 1914 called “The Price of Principle.” Boyle went on to write several more Blackie stories that were collected into a book of short stories in 1919. The character as created by Boyle was a bit more hardened than the radio version.
Chester Morris whose fame grew from the B film versions that most people are familiar with, agreed to star as Blackie on radio. The radio version began as a summer replacement for Amos n Andy on NBC in June 1944. It too was sponsored by Rinso Soap. When the series ended in the fall it did not return.
However, in 1945, the Frederick Ziv company put up money for the series to be made. None of the original characters returned but instead Richard Kolmer, who some might know as the husband of columnist Dorothy Kilgallen stepped into the role.