Mary Boyle Seitz; Scenarist for MGM

Mary Boyle Seitz, 93, scenarist for the 1930 motion picture that afforded John Wayne his initial break. She outlined the characters, plot and scenes for “The Big Trail,� which gave Wayne his first leading role. A native of Canada, Seitz joined MGM Studios on its opening day in 1924. She worked for such luminaries as Irving Thalberg, David O. Selznick and Raoul Walsh over the next decade. She left the film business in 1934 to marry John F. Seitz, a pioneering cinematographer who shot such films as “The Four Horsemen of the Apocalypse� and “Sunset Boulevard.� She devoted the rest of her life to family and charitable endeavors. On Monday in Los Angeles.