Mark David Chapman was born on May 10, 1955, in Fort Worth, Texas. His father, David Chapman, served as a staff sergeant in the United States Air Force. His mother, Diane Pease, worked as a nurse. Mark had a younger sister named Susan, who was born seven years after him. As a child, Mark reported living in fear of his father, who he claimed was abusive towards his mother and emotionally distant with him. This environment led Chapman to create fantasies where he had power over imaginary "little people" that he believed lived in the walls of his bedroom.

When Mark was young, his family moved to Decatur, Georgia. He attended Columbia High School, where he faced bullying because of his lack of athletic skills. By the age of 14, Chapman was using drugs and skipping school. At one point, he ran away from home and lived on the streets of Atlanta for two weeks.

In 1971, Mark had a religious transformation and became a born-again Presbyterian. He began distributing Biblical tracts and met his first girlfriend, Jessica Blankenship. Mark worked as a summer camp counselor at the YMCA in DeKalb County, Georgia, where he was popular with the children and won an award for being an outstanding counselor.

Chapman found great significance in J. D. Salinger's novel "The Catcher in the Rye," developing a desire to model his life after its main character, Holden Caulfield. After graduating from high school, he moved to Chicago, where he played guitar in churches and night spots. He later worked for World Vision, helping Vietnamese refugees in a resettlement camp in Arkansas, which included a trip to Lebanon.

Mark then attended Covenant College, a Presbyterian liberal arts school, but struggled with his studies and experienced guilt over a previous affair. He dropped out after one semester, and soon after, his relationship with his girlfriend ended. Following this, he returned to work at the resettlement camp but left after a disagreement with a supervisor.

In 1977, Chapman moved to Hawaii. He attempted suicide by connecting a hose to his car's exhaust. The attempt failed, and he was hospitalized for clinical depression. His mother later joined him in Hawaii after his parents began divorce proceedings.

In 1978, Mark traveled around the world for six weeks, inspired by the story "Around the World in 80 Days." He visited major cities across multiple countries. The trip ended with a visit to his family in Atlanta. Afterward, he entered a romantic relationship with his travel agent, Gloria Abe, whom he married on June 2, 1979.

Chapman then worked at Castle Memorial Hospital as a printer, but he was eventually fired and later quit after an argument with a nurse. Following this, he took a job as a night security guard and began drinking heavily to deal with his depression.

As his mental health worsened, Chapman developed various obsessions, including art, music, and particularly John Lennon, a former member of The Beatles. By September of 1980, he expressed feelings of losing control in a letter to a friend, stating, "I'm going nuts." Up until that point, he had no criminal convictions.

On December 8, 1980, Mark David Chapman murdered John Lennon in New York City. Chapman had been planning the murder for about three months. He was a fan of Lennon and the Beatles but became angry with Lennon due to his comments about religion and his lifestyle. He believed that Lennon preached love and peace while living extravagantly. One of Chapman's influences was the book "The Catcher in the Rye," and he sought to emulate its main character.

On the day of the murder, Chapman was present outside Dakota, the apartment building where Lennon lived. Earlier in the day, he interacted with fans and even met Lennon's housekeeper. Around 5 p.m., as Lennon and his wife, Yoko Ono, were leaving for a recording session, Chapman approached Lennon under the pretense of asking for an autograph. He held out a copy of Lennon's album "Double Fantasy."

When Lennon approached, Chapman shot him five times with a .38 revolver. Four of the bullets hit Lennon in the back and shoulder. After the shooting, Chapman did not flee the scene. Instead, he sat down and began reading "The Catcher in the Rye." When police arrived, he was arrested without incident. Lennon was rushed to Roosevelt Hospital but was pronounced dead on arrival.

During initial interviews, Chapman confessed that he had used hollow-point bullets to ensure Lennon's death. He was later charged with second-degree murder, the most serious charge in New York for killing someone who was not a law enforcement officer. Following his arrest, mental health evaluations took place. Many psychologists concluded that Chapman was experiencing severe mental health issues at the time of the murder.

Chapman initially planned to plead not guilty by reason of insanity but ultimately decided to change his plea to guilty. During sentencing, he was handed a sentence of twenty years to life in prison. After his conviction, he was imprisoned at Attica Correctional Facility and has been denied parole multiple times. Each time, the parole board cited concerns for both public safety and Chapman's mental state, along with the lasting impact of his crime.