Hello username
The only information that I was able to find about the American pilot you are interested in is that contained on the 4th Fighter Group web site:
http://www.fourthfightergroup.com/resource/kelly.html. Apparently the only claim that he is credited with is that recorded on 31 July 1942. What new information has come to light suggesting that he was the fellow who downed Pflanz?
Horrido!
Leo