The cause was heart disease, his nephew Robert Rosenthal said.
Mr. Mulligan received an Academy Award nomination for the film, based on Harper Lee’s Pulitzer Prize-winning novel about rape, racism and injustice in the Depression-era South. Gregory Peck won an Oscar for his portrayal of Atticus Finch, the Alabama lawyer who defends a black man (played by Brock Peters) falsely accused of raping a white woman. The film also won Oscars for its screenplay, by Horton Foote, and for art direction.
In interviews over the years, Robert Mulligan was often asked how a boy from the Bronx developed such an affinity for films with small-town Southern settings. The answer, he said, lay in the shared passion of both places for spinning fabulous yarns. As he told The Boston Herald in 1991: “Coming from Bronx Irish is hardly Southern. But there was that sense of the Irish storytellers, the fairy tales.”