Mark David Chapman was born on May 10, 1955, in Fort Worth, Texas. His father, David Chapman, was a staff sergeant in the U.S. Air Force and his mother, Diane (née Pease), was a nurse.

His younger sister, Susan, was born seven years later. As a boy, Chapman stated he lived in fear of his father, who he said was physically abusive towards his mother and unloving towards him. Chapman began to fantasize about having king-like power over a group of imaginary "little people" who lived in the walls of his bedroom. He attended Columbia High School in Decatur, Georgia. By the time he was 14, Chapman was using drugs and skipping classes. He once ran away from home to live on the streets of Atlanta for two weeks. He said he was bullied at school because he was not a good athlete.

In 1971, Chapman became a born-again Presbyterian and distributed Biblical tracts. He met his first girlfriend, Jessica Blankenship, and began work as a summer camp counselor at the South De Kalb County, Georgia YMCA. He was very popular with the children, who nicknamed him "Nemo" and was made assistant director after winning an award for Outstanding Counselor. Those who knew him in the caretaking professions unanimously called him an outstanding worker.

Chapman read J.D. Salinger's The Catcher in the Rye on the recommendation of a friend. The novel eventually took on great personal significance for him, to the extent he reportedly wished to model his life after its protagonist, Holden Caulfield. After graduating from Columbia High School, Chapman moved for a time to Chicago and played guitar in churches and Christian night spots while his friend did impersonations. He worked successfully for World Vision with Vietnamese refugees at a resettlement camp at Fort Chaffee in Arkansas, after a brief visit to Lebanon for the same work. He was named an area coordinator and a key aide to program director David Moore, who later said Chapman cared deeply for the children and worked hard. Chapman accompanied Moore to meetings with government officials, and President Gerald Ford shook his hand.

Chapman joined Blankenship as a student at Covenant College, an evangelical Presbyterian liberal arts college in Lookout Mountain, Georgia. However, Chapman fell behind in his studies and became obsessed with guilt over having an affair. He started having suicidal thoughts and began to feel like a failure. He dropped out of Covenant College after just one semester and his girlfriend broke off their relationship soon after. Chapman returned to work at the resettlement camp but left after an argument. He then worked as a security guard, eventually taking a week-long course to qualify as an armed guard. After dropping out of college, Chapman went to Hawaii, where he attempted suicide by carbon monoxide asphyxiation. He connected a hose to his car's exhaust pipe but the hose melted and the attempt failed. A psychiatrist admitted Chapman to Castle Memorial Hospital for clinical depression. Upon his release, he began working at the hospital. After Chapman's parents began divorce proceedings, his mother joined him in Hawaii.

In 1978, Chapman went on a six-week trip around the world. The vacation was partly inspired by the film Around the World in Eighty Days. He visited Tokyo, Seoul, Hong Kong, Singapore, Bangkok, Delhi, Beirut, Geneva, London, Paris and Dublin. He began a relationship with his travel agent, a Japanese American woman named Gloria Abe, whom he married on June 2, 1979. Chapman got a job at Castle Memorial Hospital as a printer, working alone rather than with staff and patients. He was fired by the hospital, rehired, then got into a shouting match with a nurse and quit. After this, Chapman took a job as a night security guard and began drinking heavily. He developed a series of obsessions, including artwork, The Catcher in the Rye, music and the musician John Lennon. In September 1980, he wrote a letter to a friend, Lynda Irish, in which he stated, "I'm going nuts." He signed the letter, "The Catcher in the Rye." Chapman had no criminal convictions prior to his trip to New York City to kill Lennon.

Murder of John Lennon

Motive and planning

Chapman allegedly started planning to kill English musician John Lennon three months prior to the murder. A longtime fan of Lennon's band the Beatles, Chapman turned against Lennon following a religious conversion, and was angry about Lennon's highly publicized 1966 comment that the Beatles were "more popular than Jesus." Jan Reeves, the sister of one of Chapman's friends, reported that Chapman "seemed really angry" toward Lennon and spoke frequently about Lennon's claim, saying it was blasphemy. Some members of Chapman's prayer group made a joke in reference to Lennon's song "Imagine": "It went, 'Imagine, imagine if John Lennon was dead.'" Chapman's childhood friend Miles McManushe recalled that he said that the song was "communist".

Chapman had also been influenced by Anthony Fawcett's John Lennon: One Day at a Time about Lennon's lifestyle in New York. According to his wife Gloria, "He was angry that Lennon would preach love and peace but yet have millions". Chapman later said: "He told us to imagine no possessions and there he was, with millions of dollars and yachts and farms and country estates, laughing at people like me who had believed the lies and bought the records and built a big part of their lives around his music." He also recalled having listened to Lennon's John Lennon/ Plastic Ono Band album in the weeks before the murder:

I would listen to this music and I would get angry at him, for saying that he didn't believe in God… and that he didn't believe in the Beatles. This was another thing that angered me, even though this record had been done at least ten years previously. I just wanted to scream out loud, "Who does he think he is, saying these things about God and heaven and the Beatles?" Saying that he doesn't believe in Jesus and things like that. At that point, my mind was going through a total blackness of anger and rage. So I brought the Lennon book home, into this The Catcher in the Rye milieu where my mindset is Holden Caulfield and anti-phoniness.

Chapman's planning has been described as "muddled." Over the years, Chapman has both supported and denied whether he felt justified by his spiritual beliefs at the time or had the intention of acquiring notoriety. The only time he made a public statement before his sentencing — and for several years afterward — was during a brief psychotic episode in which he was convinced that the meaning of his actions was to promote The Catcher in the Rye, which amounted to a single letter mailed to the New York Times asking the public to read the novel. According to Chapman, he had an alternate hit list of potential targets in mind, including Beatles bandmate Paul McCartney, talk show host Johnny Carson, actress Elizabeth Taylor, actor George C. Scott, former first lady Jacqueline Kennedy Onassis, just-elected US president Ronald Reagan, and Hawaii governor George Ariyoshi. In 2010, he said that the only criterion for the list was being "famous", and that he chose Lennon out of convenience. Journalist James R. Gaines, who interviewed Chapman extensively, concluded that Chapman did not kill Lennon to become a celebrity.

It is rumored that Chapman traveled to Woodstock, New York during one of his New York visits in search of Todd Rundgren, another target of obsession. Chapman was wearing a promotional T-shirt for Rundgren's album Hermit of Mink Hollow when he was arrested and had a copy of Runt. The Ballad of Todd Rundgren in his hotel room. Rundgren was not aware of the connections until much later. On the day of the murder, singer David Bowie was appearing on Broadway in the play The Elephant Man. "I was second on his list," Bowie later said. "Chapman had a front-row ticket to The Elephant Man the next night. John and Yoko were supposed to sit front-row for that show too. So the night after John was killed there were three empty seats in the front row. I can't tell you how difficult that was to go on. I almost didn't make it through the performance."

Timeline

• 2000: At the 50-minute hearing, Chapman said that he was not a danger to society and that Lennon would have approved of his release. The parole board concluded that releasing him would "deprecate the seriousness of the crime and serve to undermine respect for the law" and that Chapman granting media interviews represented a continued interest in "maintaining [his] notoriety." They noted that Chapman had a good disciplinary record while in prison, but he had been in solitary confinement and did not have access to "anti-violence and/or anti-aggression programming." Correctional Association of New York lawyer Robert Gangi said that he thought it unlikely that Chapman would ever be freed because the board would not risk the "political heat" of releasing John Lennon's killer.
• 2002: The board stated again that releasing Chapman after 22 years in prison would "deprecate the seriousness" of the crime, although his behavioral record continued to be positive, yet it was no predictor of his potential community behavior.
• 2004: The parole board held a third hearing and declined parole yet again. One of the reasons given by the board was that Chapman had subjected Yoko Ono to "monumental suffering by her witnessing the crime." Another factor was concern for Chapman's safety; several Lennon fans threatened to kill him upon his release. Ono's letter opposing his release stated that Chapman would not be safe outside of prison. The board reported that its decision was based on the interview, a review of records, and deliberation. By this time, approximately 6,000 people had signed an online petition opposing his release.
• 2006: The parole board held a 16-minute hearing and concluded that his release would not be in the best interest of the community or his own personal safety. On the 26th anniversary of Lennon's death, Ono published a one-page advertisement in several newspapers, saying that December 8 should be a "day of forgiveness," but she was not sure if she was ready to forgive Chapman.
• 2008: Chapman was denied parole at his fifth hearing "due to concern for the public safety and welfare."
• 2010: In advance of Chapman's scheduled sixth parole hearing, Ono said that she would again oppose his parole, stating that her safety, that of John's sons, and Chapman's would be at risk. She added, "I am afraid it will bring back the nightmare, the chaos and confusion once again." The parole board postponed the hearing in September, stating that it was awaiting additional information to complete Chapman's record. On September 7, the board denied Chapman's latest parole application, with the panel stating that "release remains inappropriate at this time and incompatible with the welfare of the community."
• 2012: Chapman's seventh parole hearing was held before a three-member board, and they announced the next day that it was denied, on the grounds that they believed he would reoffend again. "Despite your positive efforts while incarcerated, your release at this time would greatly undermine respect for the law and tend to trivialize the tragic loss of life which you caused as a result of this heinous, unprovoked, violent, cold and calculated crime."
• 2014: Chapman's eighth parole application was denied. Chapman told the board, "I am sorry for being such an idiot and choosing the wrong way for glory.… I found my peace in Jesus. I know him. He loves me. He has forgiven me. He has helped in my life like you wouldn't believe." The board was unmoved, telling Chapman that it believed that "there is a reasonable probability that you would not live and remain at liberty without again violating the law."
• 2016: Denied for the ninth time. Chapman said that he now saw his crime as being "premeditated, selfish and evil."
• 2018: Denied for the tenth time. The parole board wrote to Chapman that he was at low risk to reoffend, but that he "admittedly carefully planned and executed the murder of a world-famous person for no reason other than to gain notoriety. While no one person's life is any more valuable than another's life, the fact that you chose someone who was not only a world-renowned person and beloved by millions, regardless of pain and suffering you would cause to his family, friends, and so many others, you demonstrated a callous disregard for the sanctity of human life and the pain and suffering of others. This fact remains a concern to this panel."
• 2020: Chapman's eleventh parole hearing is scheduled for August.