Fresh evidence casting doubt on the conviction of a woman for the murder of a boy she was babysitting, has been uncovered by BBC Newsnight.
Suzanne Holdsworth, from Hartlepool, is serving life after a court was told she smashed Kyle Fisher against a banister with as much force as a 60mph crash.
The two-year-old died in hospital with a massively swollen brain but only some bruising on the outside of his head.
A leading neuro-pathologist says it is "unlikely" an impact caused his death.
Holdsworth, 37, who worked at the check-out at Asda supermarket in Hartlepool, has always said she did not commit the crime.
Her partner, Lee Spencer, and their two daughters, Lesley, 19 and Jamie-Leigh, 13, have never believed that she killed the little boy they all doted on.
The jury at Holdsworth's trial at Teesside Crown Court was told that the death took place after Kyle's mother, Clare Fisher, dropped her son off at her neighbour's in Millpool Close in July 2004 when she went clubbing.
According to the 60mph impact version of events, Kyle was left brain dead but the banister remained intact and unmarked by hair, tissue and blood.
But one of the country's most eminent neuro-pathologists, Dr Waney Squier, has dismissed the scenario as "meaningless, emotive words that have absolutely no scientific validity".
Suzanne Holdsworth was sentenced in April, 2005
She said: "A 60mph impact of a baby's head on a banister would cause massive damage to the head, massive skull fracturing.
"Kyle had bruises, he had no scalp swelling, he had no skull fractures, so I think that is extremely unlikely.'"
Kyle's father, Jon Taylor, who is separated from his mother, told the BBC: "It just happened to be that Suzanne was babysitting him.
"I could have been babysitting him, so that would mean I'd have probably ended up in jail."
Kyle's eye is at the heart of a case which may prove to be yet another grave miscarriage of justice.
Surgeons Professor Brian Avery and Sid Marks both saw Kyle in May, 2004, and planned to operate on his face.
The court heard that Kyle suffered an eye injury in 2003 after he fell from a buggy while he was being looked after by his mother.
Dr Squier told the BBC that Kyle's brain had two separate abnormalities, a congenital brain condition that can cause fits and the eye socket injury.
She said: "The brain had started to push down through that fracture into the eye socket and displacing the eye. The brain was scarred.
"So Kyle in fact had two abnormalities in his brain that would predispose him to having seizures. And seizures can kill."
The investigation into Kyle's death was led by Det Supt Tony Hutchinson of Cleveland police, an officer with 50 murder inquiries under his belt.
Det Supt Hutchinson said after the trial that Holdsworth "very calmly applied her mind as to how she would explain the injury to the authorities".
In Holdsworth's 999 call, she told the operator Kyle was "not breathing... his eyes are rolling and everything..."
The operator asked if Kyle had had a fit. Holdsworth said he had.
The operator then asked Holdsworth if Kyle had any pre-existing injury.
She replied: "He's got a hole in his head, a hole in his eye and they're going to have take his skin off to get to it. You know, his face."
The police did not take written statements from either of the two surgeons who saw Kyle in 2004.
Prof Avery, who is a dean of the Royal College of Surgeons, told the BBC: "I had potentially useful information and I was surprised that the police did not contact me."
Newsnight put a number of questions to Det Supt Hutchinson but he declined to comment. Asked how she was going to get through her third Christmas inside, Holdsworth said: "I go on the phone, pretend I'm fine because my babies and my partner are having Christmas. I go back to my room and I cry and I cry and I cry."
Since making that call, Suzanne Holdsworth has been disciplined by the prison authorities for talking to the BBC and her ability to talk to her family restricted.
John Sweeney's report is on BBC2's Newsnight at 2230 GMT on Thursday, 6 December.