A disturbed individual kills, and the media searches for reasons why. Sometimes, the killer obligingly cites a pop culture phenomenon as inspiration. Mark David Chapman, the man who shot John Lennon, saw himself as the living embodiment of Holden Caulfield, the hero of J.D. Salinger's "The Catcher in the Rye," who loudly declares his hatred of "phonies." Chapman, who considered the former Beatle a prime phony, took that hatred up one psychotic notch on Dec. 8, 1980, when he fatally shot Lennon at the entrance to his New York apartment building. Chapman perused Salinger's novel while waiting for the police.