Lucy Letby should be released immediately under house arrest until her case is reheard in the courts, the medical expert at the heart of her appeal has told The Telegraph.
Prof Shoo Lee, whose academic work was cited by the prosecution during her trial, said he was "pretty certain" she had not murdered or attempted to murder any babies.
He convened a panel of neonatologists and paediatric specialists to review each of the 17 deaths and collapses of infants in the case, and found there was a medical explanation for all of them.
Their report is being submitted to the Criminal Cases Review Commission, which investigates potential miscarriages of justice in England, after its findings were unveiled in London on Tuesday.
Prof Lee, who flew from Canada for the press conference in the capital, said he was prepared to meet the families of the victims to discuss the findings.
However, one parent of a baby boy killed by Letby dismissed the press conference, staged by her defence team, as a "publicity stunt".
The mother, who cannot be identified for legal reasons, said that "every aspect" of the panel's behaviour was "so disrespectful". She added: "It is very upsetting."
Prof Lee told The Telegraph: "It seems to me we need to make sure the legal process is able to deal with the fact they might have convicted someone incorrectly. And if so it needs to be done promptly.
"I think if someone is innocent and they are in jail, they should be let out as soon as possible. It is wrong to keep someone in jail who hasn't done a crime.
"That is just common sense. But I also understand there is a [legal] process. If they tell me it takes 15 years to get to appeal, that is too long. She has already spent several years in jail. It would seem reasonable [to release her]. There is [the option] of house arrest."
A key scientific paper, authored by Prof Lee in 1989, was used by the prosecution to help convince jurors that Letby had injected air into the bloodstreams of many of her victims.
He said he became concerned his work helped convict an innocent nurse after reading about the case and concluding that his research on air embolisms in newborns had been misinterpreted and misused by the prosecution.
Prof Lee was never called as a witness or contacted by the prosecution or defence.
Letby became Britain's most prolific serial killer of children after being convicted of the murders of seven babies and the attempted murders of seven others while working at the Countess of Chester Hospital between June 2015 and June 2016.
She is currently being investigated over several other suspicious deaths.
Prof Lee defended his role and said the families would have "better closure from the truth" about what happened at the hospital.
He believes the deaths were the result of a mixture of natural causes and a lack of expertise at the hospital.
If so many babies had died on a ward at a hospital in his native Canada it would have to close, he added.
However, the mother of one of the babies said: "We already have the truth and this panel don't speak for us."
Prof Lee, president of the Canadian Neonatal Foundation, accepted he had not sat through the evidence presented at Letby's 10-month trial in 2023 but said he had spent several weeks combing through 35,000 pages of medical evidence supplied by her defence lawyer.
In an interview with The Telegraph at a hotel in Kensington, in central London, before his flight home, the 68-year-old said he was convinced of Letby's innocence.
He was also convinced that his knowledge of neonatal care, and what can go wrong in a special baby care unit, was far superior to the testimony provided by the prosecution at the trial.
Prof Lee told The Telegraph: "Our hearts go out to the families. We understand their stress and anguish and it is difficult for them to revisit this but we also know they want to know the truth and we are here to tell the truth. At the end of the day they will have better closure from the truth."
He said he was prepared to meet the families "not at this time but later on perhaps", adding: "Right now there is a legal process and I'm not sure it is appropriate but I would be happy to meet with them at the right time."
Born in Singapore, he is widely recognised as one of the world's most eminent neonatologists, having studied in Canada and the US.
He was awarded the Order of Canada, an insignia which he wears proudly on his suit lapel, the honour bestowed on him for transforming neonatal care in the country from "not very good" to the "best in the world" over the course of a decade at the turn of the century.
It is in some ways surprising that he is so certain of Letby's innocence.
While he has not seen all the evidence, there is no doubt in his mind.
His panel is in total agreement. The cases were shared among them to speed up the process. They studied medical files, expert witness statements and, where they existed, photographs in the search for what happened at the hospital.
"We are pretty certain that the medical evidence says that there is no malfeasance," insists Prof Lee. "So if there's no malfeasance, there's no murder. And if there's no murder, there's no murderer."
He accepts the court might have heard "other evidence" but adds: "What I can tell you is that the medical evidence says there's no murder."
Prof Lee also defended his intervention, acknowledging he was "a foreigner" and unaware of the workings of the British legal system, but said he remained confident of his position.
"You can say you're not 100 per cent certain because you weren't there. It's true, but I'm also not 100 per cent certain that my plane is not going to crash when I go home."
The campaign to clear Letby has begun to gain traction with an effective defence now being run by Mark McDonald, the convicted nurse's new barrister.
Prof Lee took up the offer of convening the panel - he is doing it all for free and says he paid for his own flights and accommodation in London - on the agreement with the defence team that the findings of their report would be published, regardless of whether its conclusions were "favourable or unfavourable" to Letby.
Needless to say, the partial report made public so far, which runs to 40 pages including only seven pages of summaries of cases involving seven babies, concluded that "death or injury of affected infants were due to natural causes or errors in medical care".
It identified numerous failings at the Countess of Chester Hospital, including "inadequate staffing", "lack of training" and even "poor plumbing and drainage" as factors that accounted for a higher than expected death toll at the hospital, rather than Letby's murderous spree, as a jury found at the end of the trial.
Prof Lee runs through some of the cases and the conclusions drawn from "35,000 pages of records" the panel examined.
He raised questions over the prosecution's reliance on Dr Dewi Evans, its lead expert witness.
Dr Evans, a consultant paediatrician, had retired "15 years ago", said Prof Lee, who retired in 2021, and who he said was not a specialist neonatologist.
It is understood Dr Evans is expected to respond to the defence panel's report next week after he has had time to examine its findings.
Dr Evans, The Telegraph understands, fully stands by his testimony and his certainty that the babies in Chester were murdered. It is understood that he has raised his own concerns that the defence panel of specialists has succumbed to "groupthink" in reaching its conclusions.
Prof Lee told The Telegraph: "How much expertise does he really have in this area? And secondly, is he out of date? In my opinion, if you're out of practice for five years, you're probably out of date."
He added: "How is it that the expert panel found a lot of problems with the medical care provided to these babies, and the expert witness found none?"
Prof Lee also suggested that the Thirlwall inquiry into how Letby got away with murder should be paused.
Prof Lee said: "If there is no murderer, then the question is, is that a pertinent inquiry? And I don't know the answer to that. I'm just raising the question, is that still a pertinent inquiry?
"It was set up with the assumption that she was guilty. Now that we have brought this new information forward, saying that we don't think there was a murder, I think it's up now to the judicial system to say, well, is that still a relevant question?"
Prof Lee has not met Letby and has no intention of doing so. He does not want his judgment and "objectivity" clouded by talking to her or her parents.
He appears sympathetic to the pain his intervention has caused to the grieving families.
"I have looked after babies for 40 years," he said, "And families want to know the truth. They don't want you to sugarcoat things. They don't want you to lie about things. They want to know what really happened.
"They want that, even if it's painful. And I think that these families have been through a very traumatic journey, because first they were told one thing, then they were told there was a murder, and now people are saying not a murder again.
"So this is all very confusing and very troubling, but at the end of the day, I think the families want to know the truth, and we are able to bring the truth, I think they will have better closure, and they will appreciate it at the end, and we will walk them through it."
Letby's victims, he insists, will come to "appreciate knowing the truth", adding: "It may be very hard to swallow. Many things in life are hard to swallow."
For the parents whose lives have been ruined, they already know their truth: that Lucy Letby murdered their precious babies. It's hard to see them accepting Prof Lee's version of events.