Bad medical care and natural causes led to the deaths of babies said to have been harmed by British nurse Lucy Letby, a panel of international medical experts has concluded.
The team of 14 neonatologists and paediatric specialists said it "did not find any murders" after presenting its "impartial evidence-based report".
Letby, 35, from Hereford, is serving 15 whole-life sentences after she was convicted at Manchester Crown Court of murdering seven infants and attempting to murder seven others, with two attempts on one of her victims, between June 2015 and June 2016.
Chairman Dr Shoo Lee told reporters at a two-hour news conference in London that the panel had detected a number of medical problems at the Countess of Chester Hospital during the relevant period.
These included, he said, poor skills in resuscitation and inserting breathing tubes, a lack of understanding of some basic procedures, along with misdiagnoses and unsafe delays in treatment of acutely poorly babies.
Evidence of inadequate numbers of appropriately-trained staff, work overload, lack of teamwork and caring for ill babies "probably beyond their expected ability of designated level of care" was also found, Dr Lee added.
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He said the hospital would have been shut down if it was in his homeland of Canada.
"Death or injury of all the affected infants were due either to natural causes or to errors in medical care.
"There were serious problems related to medical care of patients at this hospital.
"In summary, ladies and gentlemen, we did not find any murders.
"In all cases, death or injury were due to natural causes or just bad medical care," Dr Lee said.
"In our opinion, the medical opinion, the medical evidence doesn’t support murder in any of these babies - just natural causes and bad medical care.
"I hope our findings bring comfort and closure to the families of the affected infants and our hearts and sympathies go out to them."
'Overwhelming evidence that the convictions are unsafe' - Letby barrister
The prosecution at Letby’s trial said she used various means to attack infants including injecting air into their bloodstreams which caused an air embolism, a blockage to the blood supply.
Dr Lee co-authored a 1989 academic paper on air embolism in babies which featured prominently during the ten-month court case and was used by the prosecution to highlight a variety of skin discolorations observed in babies.
But Dr Lee told the news conference that he had recently updated his paper and had found no cases of skin discoloration linked to air embolism by the venous system, and added: "So let’s do away with that theory".
The panel’s full report will be given later this month to Letby’s barrister Mark McDonald who said: "There is overwhelming evidence that the convictions are unsafe.
"If Dr Shoo Lee and the panel are correct, no crime was committed.
"If no crime was committed, that means a 35-year-old woman is currently sitting in prison for the rest of her life for a crime that just never happened."
Letby's convictions will be reviewed by the Criminal Cases Review Commission (CCRC), which investigates potential miscarriages of justice, after her lawyers made an application to the body.
Mr McDonald said: "I have been working with the CCRC for over 20 years and some cases I have had in the CCRC for over seven years waiting for them to make a decision.
"But what I do know is the CCRC are taking this very seriously. They have already got a team in place, they are ready to go.
"I hope they are going to take this very seriously and deal with it very quickly, and we will be back in the Court of Appeal very soon."
He denied he was merely submitting a "rehash" of the original defence case.
Mr McDonald said: "The defence did not call an expert. So as a result all you were left with was the evidence of prosecution experts in relation to neonatology, paediatrics and pathology.
"So yes, this is fresh evidence, this is new evidence. It’s compelling evidence because of the nature of the people who are giving that evidence and it wasn’t heard by the jury.
"The reason why Lucy Letby was convicted was because of the medical evidence that was presented to the jury. That today has been demolished."
The nurse lost two bids last year to challenge her convictions at the Court of Appeal.
A public inquiry into how Letby committed her crimes is also under way, and detectives from Cheshire Constabulary are continuing their review of the care of some 4,000 babies admitted to hospital while she worked as a neonatal nurse.
