John Lennon being dead would have been more than tragic enough.

But the "Imagine" artist was murdered, fatally shot on a New York sidewalk by Mark David Chapman on Dec. 8, 1980. It's a well-trod story, but 43 years later it's the piece of Lennon's biography that somehow still continues to shock, an unfathomable violent coda to such a culturally impactful life.

Due to his forever-status as a member of The Beatles, even though they'd been broken up for almost six years, Lennon was destined to be aggressively mourned no matter the circumstances, not unlike Elvis Presley, Marilyn Monroe and other superstars who died too young.

And their demises remain haunting in their own ways. But when 50,000 people gathered in Central Park six days after Lennon was killed, part of a worldwide 10-minute vigil planned for 2 p.m. ET by Lennon's widow Yoko Ono, a particular sign stood out. It sported Lennon's picture between two peace signs and one word: "WHY?"

The fact that there's no real answer to that question is a big reason why Chapman ended up a celebrity in his own right, too, the world seemingly desperate to understand him. And the deep dives into his psyche never stopped, with Jared Leto undergoing one of his many drastic physical transformations to play Chapman in the 2007 film Chapter 27, adapted from one of many books about the killer and his history-altering crime.

The twisted chain of events is being probed anew in the Apple TV+ docuseries John Lennon: Murder Without a Trial, premiering Dec. 6. The three-part project features never-before-heard interviews—including with a cab driver who never forgot the strange fare who got in and claimed he was a recording engineer who worked with Lennon and Paul McCartney, the doorman at the Dakota who purportedly heard Lennon's last words, confidantes of the artist and his wife Yoko Ono, and detectives, lawyers and doctors who've been involved with Chapman's case over the years.

In the series, the cabbie, Mark Snyder, recalls his soon-to-be infamous passenger getting out of the car and, leaning in to pay, "He said, 'My name is Mark David Chapman. You'll remember my name.'"

With so much lore to sift through, here's a rundown of the most haunting details about the death of John Lennon:

Thirteen years after John Lennon appeared on the cover of Rolling Stone's first issue, released Nov. 9, 1967 (newsstand price: 25 cents), the magazine featured its final photo shoot and interview with the "Imagine" singer, journalist Jonathan Cott wrapping his last chat with the artist a few days before he died.

The media "only like people when they're on the way up, and when they're up there, they've got nothing else to do but s--t on them," Lennon, whose benign observation in 1966 that The Beatles were "more popular than Jesus" triggered all sorts of backlash against the Fab Four, told Cott. "I cannot be on the way up again. What they want is dead heroes, like Sid Vicious and James Dean. I'm not interested in being a dead f--king hero."

In September 1980, Lennon and David Sheff, who was interviewing him for Playboy, talked about the violence in the world and the so-far fruitless efforts to quell it.

"Mahatma Gandhi and Martin Luther King are great examples of fantastic non-violents who died violently," Lennon mused, per Sheff's 2020 book All We Are Saying. "I can never work that out. We're pacifists, but I'm not sure what it means when you're such a pacifist that you get shot. I can never understand that."

The last day of Lennon's life started with breakfast at Café La Fortuna with Yoko Ono, his wife of 11 years, and a haircut at Viz-à-Viz. Then it was back to the Dakota, the famed Central Park West building where he and Ono had lived since 1973, for an at-home session with photographer Annie Leibovitz, who was snapping the couple for Rolling Stone.

"John came to the door in a black leather jacket," Leibovitz recalled, per Smithsonian Magazine, "and he had his hair slicked back. I was thrown a little bit by it. He had that early Beatle look."

She knew RS editor-in-chief Jann Wenner wanted her to capture Lennon solo, but the musician insisted it be him and his wife. "I want to be with her," Leibovitz recalled him saying.

The photo shoot resulted in the iconic picture of a completely naked Lennon curled around a fully clothed Ono (who refused to undress), the couple lying on the plush white carpet in their living room.

Leibovitz told RS decades later, "I remember peeling the Polaroid and him looking at it and saying, 'This is it. This is our relationship.'"

Instead of being the cover image for the publication's planned spread heralding the couple's album Double Fantasy, it served as the cover of their Jan. 22, 1981, Lennon tribute issue.

After finishing up with Leibovitz, Lennon went downstairs (at one point he and Ono owned five units in the building) to tape an interview with Dave Sholin and Laurie Kaye for RKO Radio. They all had to take their shoes off, Sholin recalled, but Lennon "loosened everybody up immediately."

The father of then-17-year-old Julian with ex-wife Cynthia Lennon and 5-year-old Sean with Ono described his typical routine: "I get up about six. Go to the kitchen. Get a cup of coffee. Cough a little. Have a cigarette." He also watched Sesame Street with Sean, Lennon noting, "I make sure he watches PBS and not the cartoons with the commercials—I don't mind cartoons, but I won't let him watch the commercials."

Among his poignant musings that afternoon, Lennon—who had just turned 40 on Oct. 9—again touched on mortality. "I hope I die before Yoko," he said, "because if Yoko died I wouldn't know how to survive. I couldn't carry on."

But otherwise, Sholin said, Lennon "was just bubbling over with enthusiasm with everything in his life. He felt like that was it; he had turned the page and was starting another chapter."

At around 5 p.m. on Dec. 8, 1980, Lennon and Ono headed out for a studio session at the Record Plant to continue work on a remix of "Walking on Thin Ice."

As they were leaving the Dakota, a man asked Lennon for an autograph, extending his copy of Double Fantasy. The "Give Peace a Chance" singer dutifully stopped to sign the album, scrawling "John Lennon 1980." The seemingly innocuous moment was captured by photographer Paul Goresh.

After a few hours in the studio, Lennon and Ono opted to go back home to say goodnight to Sean instead of go right to dinner with producer David Geffen.

At 10:45 p.m., Lennon and Ono's limo dropped them off on West 72nd Street, in front of the gated arched entryway to the Dakota. Lennon was a few paces behind his wife, carrying a stack of tapes, when Mark David Chapman—the same guy who got his autograph outside the building hours earlier—shot the musician four times with a .38 revolver, hitting him twice in the back and twice in the shoulder.

Chapman didn't flee the scene. And because truth is stranger than fiction, the 25-year-old really did drop his gun, pull a paperback copy of Catcher in the Rye out of his coat pocket and start to read. He was arrested within minutes by the NYPD officers who were on night patrol nearby and were first to respond to a report of shots fired at 1 West 72nd St.

Not wanting to wait for an ambulance, police lay Lennon in the back of a squad car and took him to what was then St. Luke's Roosevelt Hospital, about a mile away, where he was pronounced dead at 11:15 p.m.

Millions of people, including Rolling Stone editor Wenner, found out that Lennon had been killed when ABC Sports announcer Howard Cosell shared news of the "unspeakable tragedy" during Monday Night Football.

Wenner walked across Central Park to the Dakota as soon as he heard. "There was a bit of singing and people holding candles," he shared in RS. "People genuinely didn't know what to do."

In All We Are Saying, journalist Sheff recalled getting on the first flight possible to New York and going straight to the Dakota. By the early morning of Dec. 9, thousands of people were clustered in Central Park, weeping and playing Lennon's music on boom boxes. His voice was also coming from the seventh floor of the Dakota, where Ono had retreated to their bedroom to listen to her late husband's music.

Sean Lennon said he didn't know what had happened until a few days later.

"I remember it really clearly, someone saying my mom wants to talk to me," the musician told Rolling Stone in 1998. "I had to go into the bedroom, and my mom was in bed. She'd obviously been in bed for days. I remember kind of glancing at a headline on a newspaper. I could barely read; I didn't really know what it meant."

He recalled trying to be strong for his mother, even telling her she was young and would find someone else to be with ("which was an intense thing to say, now that I think about it"), but then ran into his room and "started crying hysterically."

"Hey Jude" inspiration Julian Lennon, who was living in the U.K. with his mom at the time, said that he and his father had just started talking more not long before he was killed.

John played "Starting Over" for him over the phone, Julian told BBC Radio 2 in 2020, and he remembered saying he loved it. Then he listened to Double Fantasy and loved that, "and then obviously, what happened, happened. I just remember that as being the last kind of moments, listening to him being extremely happy in a happy place, and doing what he loved...I was very happy for him and looking forward to seeing him again."

Chapman was charged with second-degree murder. He had confessed to pulling the trigger and told police he used hollow-point bullets because he intended to kill Lennon.

A number of psychiatrists and psychologists evaluated Chapman in the months after the shooting. Six experts working with his lawyers judged him to be psychotic, five diagnosing him with paranoid schizophrenia, while another thought his symptoms were more in line with manic depression. The prosecution's three experts agreed he was mentally ill, yet determined he was competent to stand trial.

In January 1981, Chapman pleaded not guilty by reason of insanity. But against the advice of his attorney, who told the court he still had "serious questions" about his client's competency to make such a decision, Chapman entered a guilty plea on June 22, 1981. He told the judge that God had willed him to do so and he would never change his plea, nor appeal.

On Aug. 24, 1981, Chapman was sentenced to 20 years to life in prison and ordered to undergo psychiatric treatment.

The 2007 film Chapter 27, starring Jared Leto as Chapman, derived its title from the fact that J.D. Salinger's seminal 1951 novel The Catcher in the Rye only has 26 chapters. As in, this was Chapman writing the next chapter of his own Holden Caulfield-esque unraveling.

From jail after his arrest, Chapman sent the New York Times a handwritten note in which he encouraged everyone to read Salinger's "extraordinary" book, as it would ''help many to understand what has happened."

''If you were able to view the actual copy of The Catcher in the Rye that was taken from me on the night of Dec. 8, you would find in it the handwritten words 'This is my statement,'" Chapman wrote. ''Unfortunately I was unable to continue this stance and have since spoken openly with the police, doctors and others involved in this case. I now fully realize that this should not have been done for it removed the emphasis that I wanted to place on the book."

While the copy he spoke of was confiscated as evidence, he acquired another that he'd bring with him to court. On the day of his sentencing, when asked if he had anything to say, Chapman read the passage that invokes the title, when Holden describes his ideal pastime to little sister Phoebe: preventing children from falling off the edge of a cliff as they played in a field of rye.

Chapman remains incarcerated at Green Haven Correctional Facility in New York and his parole has been denied 12 times to date (Ono has opposed his release every time), most recently in 2022. The now-68-year-old is still married to Gloria Abe, his wife since 1979, and they're reportedly allowed one 44-hour conjugal visit a year.

"Thirty years ago I couldn't say I felt shame and I know what shame is now," Chapman said during his 2018 parole hearing. "It's where you cover your face, you don't want to, you know, ask for anything...As each year goes by, I feel more and more shame. What it comes down to is I am sorry for my actions. I am sorry for my crime."

Back in 2010, he said that he basically did it for the fame.

"I felt that by killing John Lennon I would become somebody," he said, "and instead of that I became a murderer, and murderers are not somebodies."

Ono continued to live in the apartment she shared with Lennon until earlier this year, when the 90-year-old relocated to her farm in the Catskills, in upstate New York. Her spokesman told the New York Times in July that she still owns her residence at the Dakota.

"It would have been a lot stranger to run away," Sean Lennon, who grew up with his dad's fans even gathering for his birthday outside the building, told Rolling Stone in 1998. "The Dakota was all we had left of him. Memories and everything. How could we leave? What are we going to do? Run away and pretend he never existed? No. It would be denial. We lived there, and that's where he lived. That's where we started the family. It was out of respect for him, and out of respect for the family."

"But to this day," Sean added, "when I walk into the Dakota with my mom, I make sure she walks in front of me. I can't tell you how many dreams I've had about being shot, man. I can't tell you how many dreams I had when I was a little kid about my mom getting shot."

For more true crime updates on your need-to-know cases, head to Oxygen.com.