Why Letby case is under more scrutiny than ever

The case of Lucy Letby is at an unusual stage.

Officially, nothing has changed since August 2023 when the neonatal nurse became the most prolific child serial killer in British legal history.

But doubts over her guilt have been gaining traction thanks to her new legal team and high-profile supporters, including the Tory MP Sir David Davis.

The Thirlwall Inquiry, which was set up to examine the circumstances of how Letby killed patients under the noses of her colleagues at the Countess of Chester Hospital, is due to hear closing submissions at Liverpool Town Hall.

But early on, its chair Lady Justice Thirlwall indicated it would not entertain questions about her guilt or innocence.

Here we look back at why her case is attracting more scrutiny than ever before.

A nine-month trial at Manchester Crown Court heard that between June 2015 and June 2016 Letby targeted tiny, vulnerable babies at the Chester neonatal unit.

She used various methods to attack them including injecting them with air, poisoning them with insulin, overfeeding them and even physically assaulting them.

A staffing rota showed she had been on duty for every suspicious death or collapse identified during that period.

After more than 110 hours of deliberation, on 18 August 2023 jurors returned their final verdicts.

Letby, then 33, was found guilty of seven counts of murder, and six out of 15 counts of attempted murder.

There was one verdict of not guilty and six counts where jurors were unable to reach a verdict.

Letby was handed 14 whole-life orders, meaning she has no opportunity for parole and will die in prison.

She later faced a retrial for the attempted murder of a baby girl and was found guilty in July 2024.

She was sentenced to a 15th whole-life order.

Letby applied for leave to appeal the 14 convictions from her original trial and the additional attempted murder.

In May 2024, the Court of Appeal dismissed her application to overturn her original convictions on the grounds that prosecution evidence was flawed.

Canadian neonatologist Dr Shoo Lee, who in the 1980s co-authored an academic paper on air embolus in babies - the blockage of blood vessels by air bubbles, claimed the prosecution had misinterpreted his findings.

But appeal judges ruled his testimony would not undermine Letby's conviction because the prosecution had not solely relied on his paper to argue for the diagnosis of air embolus.

In October, Letby was also refused leave to appeal against her 15th conviction.

In the months after Letby was convicted, rumblings emerged about the safety of her convictions.

Statisticians questioned the logic behind the staffing chart, while some medical experts said the tests that showed babies had been given insulin externally could be unreliable.

Several journalists, including Private Eye columnist and physician Dr Phil Hammond and New Yorker magazine writer Rachel Aviv penned detailed articles questioning the prosecution's case.

Last year, Sir David Davis, MP for Goole, announced that he believed a miscarriage of justice had taken place, and referred to Ms Aviv's article in the House of Commons.

But while those doubts received reasonable coverage, the questions ratcheted up significantly on 4 February this year.

With the help of Sir David, Letby's post-trial barrister, Mark McDonald, arranged an unusual press conference to present the findings of a panel of 14 international experts in neonatology and paediatrics.

Chairman of the panel was Dr Lee, who claimed that those experts had poured over trial transcripts and medical records and had reached conclusions at total odds with the prosecution experts.

He said during the press conference: "We did not find any murders.

"In all cases, death or injury were due to natural causes or just bad medical care.

"In our opinion, the medical opinion, the medical evidence doesn't support murder in any of these babies."

Dr Dewi Evans, who was the prosecution's main expert witness, maintains that those claiming Letby was wrongly convicted are mistaken or have misunderstood the way the case was put.

He told the Sunday Times that Dr Lee's paper was not a crucial cornerstone of the prosecution case.

"It's a useful paper — I don't want to do it down — but comparing how babies responded to treatment in the 1980s to how they respond to treatment in 2015, it's different," he said.

Dr Evans also clashed with Letby's barrister after Mr McDonald claimed he had "changed his mind" about how three of the babies murdered by Letby had been killed, which he refuted.

"It's highly disrespectful to the families of babies murdered and harmed by Lucy Letby," he added.

Lawyers for the parents of babies killed and attacked by Letby said they found the speculation over her guilt "deeply upsetting".

Solicitor Tamlin Bolton told the BBC: "I can't stress enough how upsetting that has been for all of the families that I represent.

"It is the families that are going through this, continuing to go through this in its enormity and sincerity."

After the press conference in February, one mother told a newspaper: "We already have the truth".

With two applications for leave to appeal rejected and a full public inquiry premised on her guilt almost finished, it would be reasonable to consider the matter settled.

But all convicted criminals in the UK have the option of making an application to the Criminal Cases Review Commission (CCRC), the statutory body set up to look for potential miscarriages of justice.

The panel of 14 experts have passed their findings to the CCRC which indicated that a review of the application would take time due to the complexity of the case.

If the CCRC concludes there is a risk that a conviction is unsafe, it can refer the case to the Court of Appeal for a full hearing.

Detectives continue investigations into other deaths and baby collapses that were not part of the original case against Letby.

Meanwhie, Cheshire Police has revealed that a criminal probe into the hospital had been widened to focus on individual staff.

The scope of the investigation will now include potential offences of gross negligence manslaughter, focussing on the action or inaction of individuals.

Det Supt Paul Hughes said several suspects had been notified but "no arrests or charges have yet been made".

The Thirlwall Inquiry is due to hear its final submissions from its core participants including the families of Letby's victims, the Countess of Chester, its former senior leaders, NHS England and other health agencies.

On 17 March, inquiry chair Lady Justice Thirlwall revealed she had received a request from former senior executives at the Countess of Chester Hospital, along with David Davis, asking her to suspend the public inquiry.

Lawyers representing chief executive Tony Chambers, medical director Ian Harvey, director of nursing Alison Kelly and HR director Sue Hodkinson made the application weeks after the panel of experts held their press conference.

They have also written to the health secretary asking for a pause.

Submissions will be heard on the topic later at Liverpool Town Hall, along with the closing statements.

Lady Justice Thirlwall's findings are expected to be published in Autumn.

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