SERIAL KILLER OR POSSIBLE MISCARRIAGE OF JUSTICE? THE LUCY LETBY DEBATE CONTINUES

Lucy Letby remains at the centre of one of Britain’s most closely watched criminal cases, more than three years after she was convicted of murdering babies and attempting to murder others at the Countess of Chester Hospital.

The former neonatal nurse was convicted in 2023 of murdering seven babies and attempting to murder six others, with a further attempted-murder conviction following a retrial in 2024. She is serving 15 whole-life orders. Letby continues to maintain her innocence.

Yet the case remains the subject of intense public and scientific debate.

Questions have been raised by some medical, scientific and statistical experts about aspects of the evidence presented at trial, particularly the medical interpretation surrounding two babies whom prosecutors said Letby deliberately poisoned with insulin.

Those questions have become part of a wider legal effort seeking to have her convictions reviewed.

QUESTIONS OVER THE INSULIN EVIDENCE

Among the most closely examined parts of the case are the convictions involving two premature babies identified in court as Baby 6 and Baby 12.

Engineering expert Helen Shannon and bioengineering professor Geoff Chase previously produced a report challenging aspects of the scientific evidence used to support the prosecution’s case that the babies had been poisoned with insulin.

The pair have continued to maintain that it was “very unlikely” that the two babies had been poisoned with insulin.

However, in September 2026, Shannon and Chase withdrew from Letby’s defence team.

Their decision did not mean they had abandoned their doubts about the two insulin convictions. Instead, they said they could not support other arguments being advanced by the defence, describing some of those arguments as inconsistent with available evidence, science and established physiology.

Letby’s barrister, Mark McDonald, rejected the suggestion that the development undermined the wider appeal effort. He has argued that other international experts have raised substantial concerns about the scientific evidence relied upon at trial.

THE THIRLWALL INQUIRY

Another major development came in September 2026 with the publication of the Thirlwall Inquiry report.

The inquiry examined what happened at the Countess of Chester Hospital, including how concerns about babies’ collapses and deaths were handled by doctors, nurses, managers and hospital leadership.

Its findings were highly critical of the hospital’s management, governance and safeguarding arrangements.

Lady Justice Kathryn Thirlwall said there had been a “complete failure to protect babies” and found that safeguarding procedures were not properly invoked when concerns arose that a member of staff might be deliberately harming babies. The report also found a prolonged delay before police were contacted.

The inquiry concluded that some collapses and deaths could have been avoided had appropriate safeguarding practices been followed.

But an important distinction remains.

THE INQUIRY DID NOT DECIDE WHETHER LETBY WAS GUILTY

The Thirlwall Inquiry was not a retrial of Lucy Letby.

Lady Justice Thirlwall explicitly stated that the inquiry did not investigate Letby’s criminal convictions or determine her guilt or innocence. It also did not examine the detailed expert evidence presented during the Crown Court trials.

Instead, its focus was on what hospital staff and organisations knew at the time, how concerns were handled and what changes are needed to protect babies from deliberate harm in neonatal units.

That means the inquiry’s findings about serious hospital failures do not, by themselves, overturn Letby’s convictions.

THE LEGAL REVIEW IS STILL UNDERWAY

Letby’s case is now being examined by the Criminal Cases Review Commission (CCRC).

The commission received a preliminary application in February 2025 and has since received additional defence material and expert reports. In February 2026, the CCRC confirmed that its review of Letby’s convictions was underway.

The CCRC has stressed that it does not decide whether someone is guilty or innocent.

Its role is to investigate potential miscarriages of justice and, where the legal test is met, refer a conviction back to an appellate court.

As of September 2026, the CCRC has not announced a decision to refer Letby’s convictions back to the Court of Appeal.

OTHER CLAIMS HAVE ALSO BEEN TESTED

The debate extends beyond the insulin evidence.

Some critics of the original prosecution have pointed to staffing pressures, the vulnerability of premature babies and possible natural or medical explanations for some of the collapses.

However, the Thirlwall report also examined several of these issues.

For example, its findings addressed concerns about the reliability of blood-test evidence and the possibility that infections such as pseudomonas could have explained some of the babies’ illnesses. The report did not accept those arguments as establishing alternative explanations for the deaths and collapses.

This is why the current debate cannot simply be reduced to a claim that the convictions have been disproved.

They have not.

A CASE STILL UNDER SCRUTINY

Lucy Letby remains legally convicted and imprisoned.

At the same time, the CCRC is examining new evidence submitted on her behalf, while some specialists continue to dispute aspects of the scientific evidence used at trial.

The recent withdrawal of two experts from her defence team has added another layer of complexity: they continue to stand by their assessment regarding the two insulin cases but have publicly rejected some other arguments being advanced in her name.

Meanwhile, the Thirlwall Inquiry has established serious failures in hospital management and safeguarding, while deliberately leaving the question of Letby’s criminal guilt outside its remit.

For now, therefore, two things can be true at the same time: Letby’s convictions remain in force, and questions about aspects of the evidence and the handling of concerns at the hospital continue to be examined.

Whether the CCRC ultimately refers any of her convictions back to the Court of Appeal remains unresolved.

The legal process — rather than public debate alone — will determine what happens next.