What book was Mark David Chapman reading when he was arrested after he had killed John Lennon?

Mark David Chapman (born May 10, 1955) is an American murderer who shot and killed John Lennon at the entrance to the Dakota apartment building in New York City on December 8, 1980. Chapman fired five times at Lennon, hitting him four times in the back, then sat down on a nearby curb and read J. D. Salinger's novel "The Catcher in the Rye" until he was arrested by the police. He has repeatedly said that written inside the novel was his statement.

Chapman's legal team intended to mount an insanity defense that would be based on expert testimony he was in a delusional psychotic state at the time of the killing. As the trial approached, Chapman instructed his lawyers he wanted to plead guilty, based on the assertion what he had decided was the will of God. After Chapman denied hearing voices, the judge allowed the plea change without further psychiatric assessment and sentenced him to a prison term of twenty-years-to life, with a stipulation mental health treatment would be provided. Chapman has been imprisoned ever since, having been denied parole nine times amidst campaigns against his release after he became eligible in 2000.