Why the Lucy Letby investigation does not address the certainty of her conviction

With the opening of the investigation into the crimes of child serial killer Lucy Letby, the final phase of one of the most significant criminal cases in recent legal history begins this week.

Over the course of two trials – the first ending in August 2023 and the second in July this year – the former nurse was found guilty of the murder of seven babies and the attempted murder of seven more while she worked in the neonatal unit at the Countess of Chester Hospital between June 2015 and June 2016.

Letby is currently serving 15 life sentences.

In recent weeks, however, several experts have raised concerns about some of the evidence presented in court and suggested that her conviction was indefensible.

But the inquiry, which begins on Tuesday and is being led by High Court judge Lady Justice Thirlwall, will not look directly at those issues. Instead, it will examine what enabled Letby to commit the offences and how the hospital dealt with concerns about her.

Experts question the certainty of the Letby convictions

After reporting restrictions were lifted in July following her final conviction, questions were raised about the evidence presented in Letby's trial.

Peter Green, former president of the Royal Statistical Society, raised doubts about the staffing plan, which showed jurors that Letby was on duty during every suspicious death or collapse during those 12 months. He told the BBC: “The plan does not include events that happened when Lucy was off duty.” There were six more deaths during that time.

The jury concluded that Letby deliberately harmed several infants by injecting air into their bloodstream, causing an air embolism that blocked their blood supply and led to a sudden and unexpected collapse. At her trial last year, her defense team claimed the evidence for this was “slim.”

The trial also found that Letby poisoned her victims with insulin. However, forensic toxicologist Prof Alan Wayne Jones has questioned the way the evidence was presented to the jury. He told the BBC that the tests carried out only measured the babies' response to insulin, not the insulin levels themselves.

On September 3, the Guardian reported that Letby scribbled messages on Post-it notes – which were presented as evidence of a confession at her trial – on the advice of counsellors she saw between July 2016 and July 2018, when she was reportedly suffering extreme stress after being released from the ward following the series of deaths.

On one note, she wrote: “I killed her on purpose because I'm not good enough to take care of her” and “I'm evil, I did this.” During the trial, prosecutor Nick Johnson asked the jury to read the note “verbatim” as a confession.

In light of these questions, Private Eye's medical correspondent Dr Phil Hammond said on Wednesday that this could be “the biggest medico-legal error of all time” and that the arguments put forward would have to be “tested in the Court of Appeal”.

However, Dr Hammond added that he had spoken at length with retired paediatrician Dr Dewi Evans, who was “convinced beyond any doubt that Letby was guilty”. Dr Evans was hired by Cheshire Police to investigate the series of collapses in the neonatal unit and gave evidence at the trial about many of the children allegedly harmed by Letby.

Furthermore, questions about the certainty of a conviction do not necessarily mean that the people raising those questions believe she could be innocent. Professor Green told the BBC: “I have no idea whether she is innocent or not. My concern is simply the possibility that this was not a certainty of conviction.”

The parents of twin boys who were victims of Letby have criticized those who questioned their convictions, saying it added further pain and suffering to the traumatic process.

“Our family is deeply shocked by the ongoing speculation about a so-called miscarriage of justice,” the parents of babies E and F, as they are known for legal reasons, told the Sunday Times.

“Certain pieces of evidence being discussed in the media are completely out of context and misrepresented. Misinformation is being spread about what happened in court. Because we were present at the trial ourselves, we know exactly what was said.”

Letby had previously tried unsuccessfully to appeal against her convictions. In May, Dame Victoria Sharp and Lord Justice Holroyde dismissed her case.

In a 59-page judgment, Dame Victoria declared Letby's appeals were “not incontestable” and refused to formally accept proposed new evidence.

She said: “The judge was therefore right in directing the jury that they must be satisfied on all the evidence that the plaintiff intentionally caused harm to a baby, with the requisite intent to murder or attempt to murder, and that her act(s) in the case of the deceased babies caused or contributed to the death.

“The prosecution did not need to prove her exact conduct.”

On Thursday, it was reported that Letby had changed her legal team to launch a new appeal attempt.

What is the subject of the investigation?

A group of experts last week called for the Thirlwall inquiry into Letby's crimes to be postponed due to doubts about the evidence.

However, a spokesman for the inquiry said it would begin as planned on Tuesday – and “will follow the Foreign Secretary's instructions”.

The investigation will focus on the conduct of hospital staff and the question of whether the police and other external bodies should have been informed earlier about the suspicions surrounding Letby.

It will also focus on the responses to the concerns raised by leaders at the Countess of Chester Hospital Trust about the nurse, and examine whether the Trust's culture, management and governance structures and processes contributed to the failure to protect the babies from her.

This means that questions about their convictions are unlikely to be raised directly during the inquiry – but it is possible that some of them will be discussed indirectly.

The study focuses on three areas:

• the experiences of the parents of the babies in the hospital.

• the conduct of those working at the hospital and how Letby was able to repeatedly kill and harm babies in the neonatal unit.

• the effectiveness of NHS management and governance structures and processes, examining relationships between different professional groups, the culture within hospitals and how these impact on the safety of newborns in neonatal units.

Once the inquiry is completed, the judge in charge of the inquiry, Lady Thirlwall, will make such recommendations to the Government as she “considers appropriate”.

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