Letby Trial: Key Witness Under Investigation Over Patient Safety Concerns

The convictions of Lucy Letby, the nurse who murdered seven babies and attempted to murder seven others at the Countess of Chester Hospital, continue to be scrutinized. A recent investigation by The Guardian has revealed that a key prosecution expert witness, Professor Peter Hindmarsh, was under investigation by the medical regulator at the time he provided crucial evidence regarding insulin poisoning. This disclosure raises further questions about the medical basis of the case, particularly as a growing number of experts argue the convictions may be unsafe.

Concerns Raised During Trial Testimony

Professor Hindmarsh, a consultant paediatric endocrinologist, testified that blood test results indicated babies F and L had been poisoned with insulin, likely injected into their intravenous feed bags. His evidence was central to the prosecution’s claim of deliberate harm, and the jury reached unanimous guilty verdicts in these two cases – verdicts that were particularly influential in the judge’s summation, allowing the jury to infer deliberate harm in other cases where the precise cause was less clear. However, the General Medical Council (GMC) opened a formal investigation into concerns about Hindmarsh’s fitness to practice on the very day he first gave evidence in November 2022.

The investigation stemmed from concerns raised by both University College London Hospitals (UCLH) and Great Ormond Street Hospital, where Hindmarsh had previously worked. Great Ormond Street had terminated his contract four months prior, in July 2022, but the reason for this termination was not disclosed to the jury during the trial. UCLH also reported “similar clinical concerns” to the GMC in December 2022, leading to restrictions on his practice – a medical tribunal determined he “may pose a real risk” to the public. Despite these concerns, and a tribunal assessment that the allegations “may have the potential to impact on his ability to act as an expert witness”, Hindmarsh was permitted to continue providing expert testimony for the prosecution. The Guardian’s investigation details how the Crown Prosecution Service opposed informing the jury about the GMC investigation, arguing it hadn’t reached a final adjudication.

Expert Evidence Under Scrutiny

The revelations about the investigation into Professor Hindmarsh come as the medical evidence presented in the Letby trial faces increasing criticism. A panel of 14 medical and scientific experts, led by Canadian neonatologist Dr. Shoo Lee, unanimously concluded that the babies died or collapsed due to natural causes and poor care on the neonatal unit, finding no evidence of murder or insulin poisoning. Dr. Lee has also specifically challenged the interpretation of his own research used by the prosecution.

These experts have questioned the reliability of the tests used to measure insulin levels, arguing they are prone to producing inaccurate results. They also dispute Hindmarsh’s calculations and the plausibility of insulin being administered via feed bags. They contend that alternative explanations for the babies’ hypoglycaemia, such as inadequate medical care, were not adequately considered. The prosecution had described the insulin cases as “incontrovertible” evidence of deliberate harm, but this assertion is now being vigorously challenged.

The Role of Hypoglycaemia in the Case

Hypoglycaemia, or low blood sugar, is a serious condition that can lead to confusion, seizures, coma, and even death. As reported by the BBC in 2022, Professor Hindmarsh testified that Child F’s blood sugar levels dropped to dangerously low levels for a prolonged period, potentially caused by insulin poisoning. However, experts now argue that hypoglycaemia in premature babies is relatively common and can be caused by a variety of factors, including difficulties with feeding and temperature regulation. Determining whether hypoglycaemia is the result of deliberate poisoning or natural causes requires careful consideration of all available evidence, and the experts now questioning the convictions believe this was not adequately done in the Letby case.

What Comes Next: A Review of the Convictions

Lucy Letby maintains her innocence and many of her supporters believe she was scapegoated for systemic failings within the neonatal unit. Her lawyer, Mark McDonald, has applied to the Criminal Cases Review Commission (CCRC) to have her case sent back to the Court of Appeal. The CCRC is currently reviewing the application, which is supported by the reports of 27 leading experts, including Dr. Lee’s panel. The CCRC’s role is to investigate potential miscarriages of justice and refer cases back to the appellate courts if they believe there is a real possibility the conviction might be overturned.

The disclosure regarding Professor Hindmarsh’s investigation adds another layer of complexity to this case. While the GMC investigation was ultimately closed when Hindmarsh voluntarily removed himself from the medical register – a process that effectively ends the investigation without a formal finding – the fact that it was ongoing during his testimony raises serious questions about transparency and the potential impact on the jury’s perception of his credibility. The CCRC will undoubtedly consider this information as part of its review, alongside the growing body of expert opinion challenging the medical basis of the convictions.

The case highlights the critical importance of rigorous scrutiny of expert evidence in criminal trials, particularly in complex medical cases. It also underscores the require for full disclosure of any potential conflicts of interest or factors that could undermine an expert’s impartiality. The outcome of the CCRC review will be closely watched, as it could have significant implications for the future of this case and for the standards of evidence required in similar trials.