Catcher in the Rye (while a shit book, with a thoroughly miserable main character) is not responsible for any murders. The people who identified with it and later killed were just as likely to commit murder with out the book. The fact that they so strongly identified with it should make us treat it like a canary in a coal mine, rather than a some trigger from the Manchurian Candidate.
Edit: Upon looking it up i found only three real world murders or attempted murders that had any link to Cather in the Rye. Of those three only in the murder of John Lennon by Mark David Chapman did the book and its themes have any significance. John Hinkley Jr. had a half dozen other books in his hotel room when he tried to kill Ronald Reagan and expressed no special interest in the book; and when Robert John Bardo killed Rebeeca Schaeffer he tossed the book on the ground after he killed her, but he was a schizophrenic Bi-polar who seemed more interest in Mark David Chapman then the book.