Kid Blue

Kid Blue is a 1973 film directed by James Frawley and starring Dennis Hopper, Warren Oates, Peter Boyle and Ben Johnson.

Bickfords former girlfriend Janet Conforto Janice Rule tracks him down and reveals that Bickford is actually a train robber known as Kid Blue. Bickford returns to his old ways and plots a crime. At the end, Preacher Bob helps the kid escape Mean John in a surprising manner.

Source: Wikipedia