Baby killing nurse Lucy Letby may have been convicted by jurors who were "misled" by allegedly faulty tests carried out on two infants who died from insulin poisoning, her lawyer has claimed. A dossier containing alternative diagnoses for the deaths of two of Letby's victims was yesterday handed to the miscarriages of justice watchdog with the revelation that its contents offered "fresh hope" that Letby could one day be freed.

Mark McDonald delivered the full findings of an international panel of 14 neonatologists and paediatric specialists to the Criminal Case Review Commission, claiming the dossier revealed significant flaws in the evidence used to convict the former nurse and would clear Letby's name. The group concluded that poor medical care and natural causes were the reasons for babies collapsing at the Countess of Chester Hospital neonatal unit, not deliberate harm by Letby. Mr McDonald said seven experts had analysed the cases of two twin boys, who Letby was convicted of attempting to murder eight months apart, and concluded the test results were unreliable.

He said they now cast "serious doubts" on her convictions as he hand-delivered the 86-page report analysing the cases of the children, known as Babies F and L, to the Birmingham offices of the Criminal Cases Review Commission this afternoon.

Also passed to the CCRC, which investigates potential miscarriages of justice, was a separate report on the full findings of a 14-strong international panel of neonatologists and paediatric specialists who say poor medical care and natural causes, not Letby, were to blame for the collapses or deaths of the 17 babies in her original trial.

Letby, 35, from Hereford, is serving 15 whole-life orders after she was convicted at Manchester Crown Court of murdering seven of those children and attempting to murder seven more, with two attempts on one of her victims, at the Countess of Chester Hospital between June 2015 and June 2016.

The barrister's intervention came hours after the senior police officer who investigated the serial baby killer hit back at "ill-informed" and "insensitive" critics questioning her guilt.

In a strongly worded statement, Detective Superintendent Paul Hughes insisted the former nurse's case had been "rigorously and fairly tested" by two juries and two sets of appeal court judges after a painstaking and complex six-year police investigation.

But he said despite this his inquiry, the judicial process and the medical experts who gave evidence are being scrutinised by "ill-informed" critics with "very partial knowledge of the facts and totality of the evidence", in what was his first public intervention.

Letby's quest for freedom is being backed by 76-year-old failed former Tory leadership candidate David Davis, the MP for Goole.

Mr Hughes said Cheshire police had chosen not to enter into a public debate about Letby's convictions for the sake of the families of the babies "who are at the very heart of this".

But he conceded there was a "public interest" in reporting the case and that "everyone is entitled to an opinion", but he insisted the families' voices "must not be lost".

He added: "Their dignity and composure in the face of intense public discussions with little sensitivity or humanity is remarkable.

"Their words are incredibly honest and powerful and must not be lost in a sea of noise. They have suffered greatly and continue to do so as this case plays out in a very public forum."

Following her two failed appeals, Letby's new defence team, led by Mr McDonald, have mounted a huge public campaign - branded a "misinformed circus" by parents of her victims - to set her free.

As he delivered two large lever arch files at noon to the front desk of the CCRC offices, in central Birmingham, he described it as a "pivotal moment" and said he hoped the watchdog "would not take long" to look at the evidence and refer Letby's case back to the Court of Appeal "as a matter of urgency."

Mr McDonald said the dossier consisted of 23 reports, from 24 experts across eight different countries, which "completely demolishes" and "blows the prosecution's case put before the jury out of the water."

"These reports show that no crime was committed," he added.

Mr McDonald revealed Letby had read the expert reports and had "new hope that the truth will come out."

He denied that he had gone "expert shopping" for medics from around the globe to support Letby's case - as lawyers for the families of her victims claim - but agreed that it was "proper" that the CCRC would want to know exactly why she failed to call any experts in her defence first time around.

However, he refused to explain why that was and instead simply said he had found experts who he insisted are "the best in the world."

In their closing submissions to the public inquiry, lawyers for the families disputed his claims and said the new expert reports were "full of analytical holes" and a "re-hash" of what had already gone before the court.

One mother also branded a press conference hosted by Mr Davis with Mr McDonald and retired Canadian neonatologist Dr Shoo Lee as a "misinformed and inaccurate media circus" which was adding to the families' distress.

Letby tried to murder Babies F and L by poisoning them with insulin, a drug which mimics the hormone that is produced by the body to lower blood sugar. The drug was kept in an unlocked fridge at the Countess and she was found guilty of adding the medication to the infants' fluid drips.

Both infants also had brothers who Letby attacked around the same time by injecting air into their bloodstreams. Baby F's brother, Baby E, was murdered in August 2015 but Baby M, the twin of Baby L, miraculously survived after almost 30 minutes of CPR, in April 2016.

The experts' findings claim that the jury at Letby's trial was "misled" because the immunoassay test, carried out by a laboratory in Liverpool, where doctors sent patients' blood for analysis, "did not meet acceptable forensic standards."

They claim the jury was wrongly told that the test was specific for the identification of insulin alone and could be relied upon. They also say they were not told about the margin for error, nor did any expert give evidence on quality control.

There was also now "convincing new evidence" that the test could give "falsely high" insulin results if certain antibodies were present in a patient's blood, the experts, including two consultant neonatologists, a retired professor in forensic toxicology and a paediatric endocrinologist, said.

According to their report, such antibodies can also be transferred from mother to baby during pregnancy causing hyperinsulinism, a condition caused when the pancreas produces too high levels of insulin leading to hypoglycaemia or low blood sugar once the child is born.

The experts also claim to have found "alternative" medical explanations for both Baby F and Baby L's low blood sugar. In Baby F's case, the experts believe he had developed the serious infection, sepsis, and wasn't getting enough supplementary glucose for several hours because the long line - the tiny catheter used to administer drugs - had 'tissued' or failed.

Both babies had restricted growth in the womb, a known risk factor for perinatal stress-induced hyperinsulinism, a type of hyperinsulinism that occurs in newborns because of problems during pregnancy or birth, they claim.

Treatment of their low blood sugar was also mismanaged by doctors at the hospital, the experts said.

Peter Hindmarsh, a consultant and specialist in childhood diabetes at Great Ormond Street Hospital and emeritus professor at University College London (UCL), gave evidence at Letby's trial that high insulin levels, coupled with low rates of C-peptide, a by-product released when the body produces insulin naturally, which was found in both babies' blood samples, proved they were poisoned by insulin given exogenously as a drug.

Significantly, Letby also accepted that the babies were poisoned when she gave evidence in the witness box in her defence, although she insisted the insulin had not been administered by her.

But the report authors disagree and claim that Baby F and Baby L's insulin and C-peptide levels were within the normal range and typical for premature infants.

It says: "Our inescapable conclusion is that this evidence significantly undermines the validity of the assertions made about the insulin and C-peptide testing presented in court."

Among other findings of the panel, in the full report also delivered by Mr McDonald today, was that a baby boy, known as Baby C, died following ineffective resuscitation from a collapse after an "acute small bowel obstruction" that went unrecognised, rather than from a deliberate administration of air into his tummy or bloodstream. This theory, however, was discounted by experts for the prosecution at the trial.

Child P, a triplet boy, was also found by the jury to have been fatally injected with air but the panel ruled he died from a collapsed lung that was "suboptimally managed".

Letby's experts said there was also no evidence of air embolism - in which air bubbles block the blood supply to the heart - in a twin boy, known as Baby E, and that bleeding he suffered was not caused by inflicted trauma but from either a lack of oxygen pre-birth or a congenital blood vessel condition.

Lady Justice Thirlwall is due to publish in November the findings from the public inquiry into how the former nurse was able to commit her crimes.

In written submissions to the inquiry, Richard Baker KC, said families of Letby's victims were concerned that medical evidence was being presented at press conferences.

Cheshire Constabulary is continuing a review of deaths and non-fatal collapses of babies at the neonatal units of the Countess of Chester Hospital and the Liverpool Women's Hospital during Letby's time as a nurse from 2012 to 2016.