Six months after killing John Lennon, Mark David Chapman entered a guilty plea in a New York courtroom. There was no question that Chapman had shot the former Beatles star outside his Manhattan residence, but few would have expected the suspect to admit guilt in a court of law.

Chapman’s lawyers had put forth a plea of not guilty by reason of insanity in the months following the December 1980 murder. Chapman appeared to suffer from major instability, having stayed at the scene of the crime reading J.D. Salinger’s The Catcher in the Rye and telling the arresting officers that he was part Holden Caulfield (the book’s protagonist) and part devil. In early 1981, he sent a letter to the New York Times, encouraging people to find all the answers in Salinger’s book.

In the meantime, more than a dozen mental health experts assessed Chapman’s mental state while he was in custody. Although the witnesses for the defense decided he was insane, the court-appointed experts determined that the man was fit to stand trial for second-degree murder.

As the trial date approached, Chapman began to disagree with the defense’s strategy to claim he was crazy (which would have resulted in a sentence at a mental hospital and not prison). He also claimed he was given better advice from a higher power. So, on June 22, 1981, Chapman pleaded guilty to the murder of Lennon.

“[It was] his own decision,” Chapman’s defense attorney Jonathan Marks told the Daily News. “He made it against my advice and on the grounds that he believes that [on] June 8 and June 10 God told Mr. Chapman to plead guilty.”

In court, Chapman calmly answered a few questions about how he had killed Lennon, including why he had chosen bullets that would “ensure John Lennon’s death.” He also admitted to considering a number of other famous targets before settling on Lennon.

“There is no question that he has felt at peace ever since God commanded him to plead guilty,” Marks said. “He is less agitated, he is experiencing real remorse for John Lennon’s family. … He has been taking minor sedatives since June 1 and he no longer believes he is the ‘Catcher in the Rye.’”

Chapman was sentenced to 20 years to life behind bars on Aug. 24, 1981 – five years less than the maximum punishment because of his guilty plea. He has spent most of his time at the Attica Correctional Facility in Attica, N.Y., before being transferred to the Wende Correctional Facility in Alden, N.Y., in 2012. Chapman has applied for parole every two years since 2000 (when he first became eligible) and has been denied every time.

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