A new twist in the sensational JonBenet Ramsey murder mystery has blown the 20-year-old case wide open yet again.
In a book published days before a recent documentary pointed the finger at her brother, the authors made the same allegation - with a few vital differences.
Nick van der Leek and Lisa Wilson, authors of current bestseller The Craven Silence, claim the six-year-old pageant queen was killed by nine-year-old Burke, but have an alternative theory about the weapon.
They also have further claims about the possible motive for him to allegedly brutally murder his sister on Christmas Day, and how his terrified parents could have covered up the shocking act at the family home in Boulder, Colorado.
Burke, now 29, has vehemently denied the accusations, and intends to sue CBS over the The Case Of: JonBenet Ramsey.
Like the documentary's team of criminal experts, South African Mr Van der Leek and Californian Ms Wilson do not credit the intruder theory.
Ms Wilson believes the evidence points to Burke harbouring "massive jealousy of JonBenet".
The little girl was the apple of her mother's eye, and was following in Patsy's footsteps as a successful beauty queen. In family newsletters sent to friends, Mrs Ramsey devotes few lines to husband John and son Burke and is "effusive" about her youngest.
"JonBenet was really put on a pedestal," Ms Wilson told news.com.au. "They doted on JonBenet. You can imagine this boy in the background, how is he processing this?"
There had been a number of unpleasant incidents between the siblings. Family friend Judith Phillips claimed Burke had hit his little sister in the face with a golf club about a year before her murder, with Mrs Ramsey telling her "things got out of hand."
The authors say the Ramseys' accounts of the event were strangely contradictory, with Mrs Ramsey's words implying an altercation between the children and Mr Ramsey later suggesting JonBenet came up behind Burke as he swung.
"There's a glaring disconnect between what John and Patsy are saying," says Mr Van der Leek.
"We see this over and over," adds Ms Wilson. "A lot of times they won't even answer."
The fact both JonBenet and Burke were regularly wetting the bed at six and nine years old points to "some trauma, some stress, some anxiety" in the house, adds Ms Wilson.
One of the most disturbing elements of the case was Burke reportedly smearing faeces over his sister's walls, possessions and in her bed, according to a housekeeper.
"There's a kind of a spitefulness going on there, a very ugly spitefulness," says Mr Van der Leek. "This beautiful younger sister who's being treated like a princess. Then you see Burke today ... he's very uncertain, very insecure.
"She's gracious, the way she carries herself, she's got a lot of investment from her mother in terms of everything, dresses and attention, all that kind of thing. Burke - he'll never be a Miss America.
"That really reached its nexus on Christmas Day."
So what do the authors think really happened on Christmas Day, 1996?
"From a child's perspective, Christmas is everything, it's the most important day of the year," says Ms Wilson.
The authors believe everything "bubbled over" after the family returned from a Christmas dinner with friends, perhaps because of tension over presents.
"We know JonBenet got a bicycle," says Mr Van der Leek. "In the photos of JonBenet on Christmas Day, you can see she's standing between two bicycles and both are ladies' bicycles with the low bar ... the other bicycle was for Patsy."
They believe Burke was furious his younger sister received such a generous gift.
The family testimonies on the issue are strange, too. At the time, Mr Ramsey said Burke was going to get a bicycle the following year. But in his recent interview with Dr Phil, Burke said he also received a bike. "Why is something like that changing?" asks Mr Van der Leek. "There's a very complex relationship going on between JonBenet and her brother and her parents."
The authors note that reporters at the time emphasised there was no evidence of a break-in and no one in Boulder should be concerned about a random killer on the loose.
But they don't buy the CBS documentary's hypothesis that Burke killed JonBenet with a torch, wiped clean of fingerprints and left in the kitchen.
"I really don't think the Ramseys would have left it out on the counter had they known Burke just used it on his sister," says Ms Wilson. "I think that was out for other reasons - they were probably using it for what they were doing down in the basement."
Instead, they claim baseball fan Burke may have bashed his sister to death with a pair of bats found in the yard far from their usual place on the patio, or with his father's golf clubs, which were stashed away in a cupboard.
The writers conjure up a picture of a middle-class mansion gripped by fear, with the parents spending the night feverishly devising a plan to protect their only remaining child, the house lights off to avoid attracting suspicion.
They claim the Ramseys flung the bats out into the snowy yard to make it look as though an intruder grabbed them on the way in and then dropped them on their way out.
The writers allege Mrs Ramsey wrote a ransom note and the parents made a garotte from nylon and a paintbrush to tie around their daughter's neck and make it look as though JonBenet had been strangled.
"The ransom note alone is massive evidence," says Mr Van der Leek. "It's pen and ink from the kitchen, Patsy's pad, the handwriting is tested across 73 different suspects and the only one they can't exclude is Patsy."
He claims the "floweriness" and "pageantry" of the three-page letter reflects Mrs Ramsey's dramatic style seen in her newsletters.
"What's really interesting about this case is there's not one piece of evidence that tells the whole story," says Ms Wilson. "Everything that was there didn't do what is was supposed to do.
"The ransom note didn't collect a ransom; the garotte didn't work like a garotte, they didn't fashion it properly; she was terribly injured, cracked across the head and strangled, yet wrapped nicely in a blanket. Nothing added up."
What is it about this case?
As proven by the popularity of recent documentaries and proliferation of online forums devoted to discussing JonBenet, the world remains gripped by this shocking murder, 20 years on.
This isn't just ghoulishness, although the case is certainly macabre: there is something about it that compels us to seek out the truth.
"JonBenet is the biggest cold case in America, and it's something that always bothered me," says Ms Wilson. "There's political things that are going on there. I had a desire to first of all find justice for this little girl but I also wanted to get back into the detail. Time and space gives you extra perspective."
The fact a grand jury voted to indict the Ramseys but Boulder's then-prosecutor, Alex Hunter, threw out the case is particularly frustrating. In fact, District Attorney Mr Hunter had never prosecuted a single case.
"Everything is settled through negotiation," says Mr Van der Leek. "It's a very wealthy individual ... it is a town full of very wealthy people."
Mr Van der Leek claims the Ramseys' flight to Atlanta and back in the days after the murder without telling police is suspicious.
He claims the family were doing what they liked, despite such strong demands from the Boulder Police for an interview that they initially refused to release JonBenet's body for burial until the Ramseys came in for questioning. Their lawyers quickly put a stop to that.
What makes this case so interesting to sleuths like Ms Wilson and Mr Van der Leek is the fact we are still hearing new information and differing accounts.
In recent A&E documentary The Killing of JonBenet: The Truth Uncovered, which supported the intruder theory, we saw psychological reports that mentioned the golf club injuries and then were apparently deliberately redacted by the program.
In Burke's Dr Phil interview, he mentioned for the first time that he got up and went back downstairs to play with a toy after being put to bed.
The CBS documentary delved into why undigested pineapple was found in JonBenet's stomach if she really had been fast asleep when they arrived home, as her parents said she was.
"What strikes you going through all the interviews is how inconsistent they are," says Mr Van der Leek. "This case which should be quite simple becomes complicated. Why is it so difficult to remember a simple thing?
"The fact there's this muddiness around really simple thing like a bike is just odd. Patsy and John were both involved in putting JonBenet to bed, but they can't quite agree on who did what.
"JonBenet never went to bed that night, she never went to bed and fell asleep."