Can't say it rang any bells with me here, but after doing a little internet searching, I did find a fictional character that went by the name of "Johnny Fletcher". And, in this character's Wiki page it states the following:
"Johnny Fletcher is a fictional character created by Frank Gruber. Fletcher is a con-man and reluctant amateur detective. The character was the protagonist of several mystery novels published between 1940 and 1964.[1] Additionally, he was featured in a feature film adaptation scripted by Gruber, and a short lived radio series."
https://en.wikipedia.org/wiki/Johnny_Fletcher
(...might this be what you're lookin' for?)