Once a Thief is a 1950 American crime film noir directed by W. Lee Wilder starring Cesar Romero, June Havoc, Marie McDonald and Lon Chaney Jr.
Margie Moore, a miserable San Francisco woman, turns in desperation to jewel robbery. She narrowly escapes apprehension in a heist and moves to Los Angeles, where she takes an honest job as a waitress. Her troubles resume when she falls in love with smooth-talking Mitch Foster, who reveals his true colors by stealing all of her money and then informing the authorities about her.
In prison with her partner-in-crime Pearl, Margie is visited by Mitch and waitress friend Flo. Mitch continues to try to extract money from her. Margie overpowers a doctor and slips away from prison disguised in the doctor's clothes. Law-enforcement authorities look for her at Mitch's and discover his illegal activities there. Mitch tries to escape, but Margie lures him to a deserted spot and shoots him.