I found this interesting article concerning early John Wayne history and Wyatt Earp.
Earp eventually moved to Hollywood, where he met several famous and soon to be famous actors on the sets of various movies. On the set of one movie, he met a young extra and prop man who would eventually become John Wayne. Wayne later told Hugh O'Brian that he based his image of the Western lawman on his conversations with Earp. And one of Earp's friends in Hollywood was William S. Hart, a well-known cowboy star of his time. In the early 1920s, Earp served as deputy sheriff in a mostly ceremonial position in San Bernardino County, California
