It's the question that has captivated America for 20 years, since the six-year-old beauty queen was found dead in her basement the day after Christmas in 1996.
This month, in the lead-up to the 20th anniversary of one of the nation's most high profile cold cases, several documentaries will air, all promising to shed new light on the infamous murder mystery.
It's unsurprising that JonBenet's case has consumed and bewildered the public over the past two decades. The unanswered questions and conspiracy surrounding her death has turned her into a figure of cultural fascination, both in her home country and around the world.
JonBenet's killer has never been brought to justice. Some still believe that it was her mother, Patsy Ramsey, while others say an intruder came into the home in Boulder, Colorado and killed the little girl while her family slept.
So much has happened since the case first broke. Patsy Ramsey died from ovarian cancer at the age of 49, three years before she and her husband John Ramsey were exonerated. She was buried beside her daughter. John then remarried in 2011.
Now, Burke Ramsey, JonBenet's older brother who was just nine years old when his sister was brutally murdered, has broken his silence.
In a series of exclusive interviews with Dr Phil McGraw, the now 29-year-old spoke about why he chose to remain silent until now, saying his life became a "chaotic nightmare" after the still-unsolved crime.
"For the last 20 years, I wanted to grow up like a normal kid, which does not include going in front of TV cameras," Burke told Dr Phil. "I was pretty sceptical of any sort of media, it just made me a very private person."
Speaking to Today about his lengthy one-on-one with Burke, Dr Phil explained the young man's bizarre composure and odd smile in front of the cameras that left viewers troubled.
"This is a very socially awkward young man but understand that from the time this happened, his parents, depending on your interpretation, either protected him or hid him ... so he has not had the social contact that most kids have growing up. When you've got reporters at the end of your driveway you couldn't go to school.
"Even now, he works as a computer analyst in computer security but he works remotely, he doesn't go into work every day, he's not around people so he's not real comfortable in a social situation. So speaking out for him was a very difficult, unusual thing."
The other lingering question viewers had was - why now, after 20 years' worth of public suspicion primarily focused on himself and his parents?
"He was starting to get bombarded, people were finding him," Dr Phil said. "He knew his anonymity was gone, he said he wanted to control the narrative. His story was going to get told, he wanted to tell it."
Despite all three being cleared by DNA evidence in 2008, many people still speculate that JonBenet's parents or her brother, the only known people to be in the home that night, could be responsible for the little girl's death.
Burke is the only one of the three family members who hasn't spoken until this time.
"The first thing I remember is my mum bursting in my room really frantic, saying, like, 'Oh my gosh, oh my gosh, oh my gosh,' running around my room, looking for JonBenet," Burke recalled.
"I remember her saying, 'Where's my baby? Where's my baby?' ... The next thing I remember is a police officer coming to my room and shining a flashlight."
Burke also recalled the moment his father broke the news to him that his little sister had died, saying, "My dad told me JonBenet is in heaven now, and he started crying, then I started crying. I was kind of like, how is this possible? I started crying. I don't think I said anything. I didn't believe it at first."
When JonBenet was killed, her tiny body was found beaten and strangled on the morning after Christmas, along with a two-and-a-half page handwritten ransom note demanding $US118,000.
Burke admitted to Dr Phil, "I know people think I did it; that my parents did it."
John Ramsey also spoke on Dr Phil in what he said will be his final interview and the last time he will comment publicly on his daughter's murder.
He detailed his happiness upon finding his little girl in the basement after being told to look for her by authorities, before he realised she was dead.
"I opened the door and there's JonBenet. I had this rush of, 'Thank God, I found her.' It was just this overwhelming sense of joy that I had found my child."
John added, "I was just hoping she'd wake up. I began to realise she wasn't going to. I started to scream, I picked her up, carried her upstairs. I was just horrified," he said. "I couldn't speak. I was just screaming."
The final part of Dr Phil McGraw's interview with Burke Ramsey airs in the US on Monday.
Channel Nine will also air the first of a three-part series called The Case Of: JonBenét Ramsey, on September 19 at 8.45pm.
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