Following the almost immediate success of
The Adventures of Sam Spade in 1946, producer-director William Spier took a
Sam Spade radio script and tweaked it to fit the mold for
The Adventures of Philip Marlowe. The latter did become a weekly radio program in 1947, but Spier had no involvement beyond this initial proposal. That radio script was found and a link is provided below for anyone who is curious to want to read the proposal, titled "The Persian."