Key Prosecution Witness in Letby Case Was Under Medical Regulator Scrutiny
An exclusive investigation has revealed that Professor Peter Hindmarsh, the crucial expert witness who provided evidence about insulin poisoning in the Lucy Letby murder trial, was under formal investigation by the General Medical Council throughout his court appearances. The jury that convicted Letby of murdering seven babies and attempting to murder seven others was never informed about the serious allegations against Hindmarsh, which included concerns about patient harm and clinical practice.
Timeline of Investigations and Trial Evidence
The GMC opened its investigation into Hindmarsh on November 25, 2022, which coincided exactly with his first day of testimony at Letby's trial. This investigation stemmed from "multiple and wide-ranging concerns" reported by Great Ormond Street Hospital, where Hindmarsh had previously worked as an honorary consultant. University College London Hospitals Trust, his primary employer, had already been conducting its own formal investigation into similar clinical concerns.
During the period between Hindmarsh's first and second appearances at the trial, significant developments occurred in the regulatory proceedings. A medical tribunal imposed severe restrictions on his clinical practice, stating he "may pose a real risk" to members of the public. The tribunal specifically noted that the allegations "may have the potential to impact on his ability to act as an expert witness." Despite these concerns, the tribunal permitted him to continue providing expert evidence for the prosecution.
Prosecution Opposition to Disclosure
The Crown Prosecution Service actively opposed informing the jury about the GMC investigation, arguing that since the allegations had not reached final adjudication, they should not be disclosed. The prosecution maintained this position even after being formally notified about the investigation in December 2022, two months before Hindmarsh's second appearance in court.
According to leaked documents obtained during the investigation, the allegations against Hindmarsh included "identified cases where harm to patients has been alleged," along with concerns about his diagnosis and treatment of patients, use of treatments in unusual age groups without adequate monitoring, inappropriate investigations, and inadequate documentation.
Critical Insulin Evidence Under Scrutiny
Hindmarsh's testimony proved particularly significant in the trial, as he provided expert analysis supporting the prosecution's claim that two babies had been poisoned with insulin. The prosecution described these insulin cases as "incontrovertible" evidence of deliberate harm, and the judge instructed jurors that if they were convinced about deliberate harm in any one case, they could infer the same in other cases.
However, numerous medical experts have since challenged Hindmarsh's insulin evidence. A panel of 14 international experts, led by renowned Canadian neonatologist Dr. Shoo Lee, concluded unanimously that the babies died or collapsed due to natural causes and poor care, with no evidence of murders, insulin poisoning, or any other deliberate harm. These experts argue that the type of tests used to measure insulin are known to produce unreliable results and should never have formed the basis of criminal charges.
Regulatory Investigation Never Concluded
The GMC investigation was ultimately never completed because Hindmarsh removed himself from the medical register through a process known as "voluntary erasure" in November 2024. This action effectively terminated the investigation without any regulatory finding against him. A GMC spokesperson confirmed that Hindmarsh is no longer registered with the organization.
When contacted for comment about the investigations, his evidence, and whether he made adequate disclosure before the trial, a spokesperson for Hindmarsh stated he had "no comment to make." Similarly, the prosecuting barrister, Nick Johnson KC, declined to comment through a representative, stating: "We do not conduct cases through journalists."
Ongoing Legal Challenges
Letby's legal team applied to the Criminal Cases Review Commission in February 2023 to have her case sent back to the Court of Appeal. This application is supported by reports from 27 leading medical experts, including Dr. Lee's panel, who argue that the prosecution's medical case was fundamentally flawed. The CCRC is currently reviewing whether there may have been a miscarriage of justice.
The revelations about the undisclosed investigation into a key prosecution witness raise significant questions about the transparency of the trial process and whether the jury had access to all relevant information when reaching their verdicts. With Letby maintaining her innocence and numerous medical experts challenging the scientific basis of the prosecution's case, these new details add another layer of complexity to one of Britain's most controversial criminal cases.
