CHICAGO — She inspired a novel and a movie starring Robert Redford when in 1949 she lured a major league ballplayer she’d never met into a hotel room with a cryptic note and shot him, nearly killing him.

After the headlines faded, Ruth Ann Steinhagen did something else just as surprising: She disappeared into obscurity, living a quiet life unnoticed in Chicago until now, more than a half century later, when news broke that she had died three months earlier.

The Cook County Medical Examiner’s Office confirmed Friday that Steinhagen passed away of natural causes on Dec. 29, at the age of 83. First reported by the Chicago Tribune last week, her identity was a surprise even to the morgue employees who knew about the 1984 movie “The Natural,” in which she was portrayed by actress Barbara Hershey....