Just stumbled across yet another serial killer with that fateful name: John Wayne Glover (see two posts ago). This one was born in 1932, so it's less clear that he was named after the movie actor. John Wayne's first movie came out in 1926, and his first starring role was in The Big Trail, released in 1930. But he didn't really become a major star until Stagecoach was released in 1939.
In any case, Glover, whose specialty was preying on elderly women, was just one more piece of proof you don't want to name your son after that American icon.