The Lucy Letby case expert witness was under fitness to practise investigation during trial
A doctor who provided crucial expert testimony about insulin poisoning in the prosecution of nurse Lucy Letby was under investigation by the medical regulator at the time due to serious concerns about his fitness to practise. The General Medical Council (GMC) opened an investigation into Professor Peter Hindmarsh, including allegations of patient harm, on the first day he testified at Letby's trial in late 2022.
The GMC investigation was ongoing when Hindmarsh testified for a second time at the Letby trial three months later. Great Ormond Street Hospital reported Hindmarsh to the GMC after a formal investigation led by his main employer, University College London hospitals trust (UCLH).
The jury in the trial of the nurse, convicted of murdering babies in the Countess of Chester hospital's neonatal unit, was never informed about any investigation into Hindmarsh, a key prosecution witness. During the investigation, a medical tribunal imposed severe restrictions on Hindmarsh's work, citing the potential risk to the public and the impact on his ability to act as an expert witness.
Despite these restrictions, Hindmarsh continued to provide expert testimony for the prosecution of Letby. The Crown Prosecution Service opposed informing the jury about the GMC investigation, arguing that the allegations had not reached a final adjudication. Ultimately, the GMC investigation was never concluded as Hindmarsh removed himself from the register, effectively ending the investigation without any regulatory findings against him.
Details of the allegations against Hindmarsh at the time of his testimony were revealed in a Guardian investigation. Letby was convicted of murdering seven babies and attempting to murder seven others, receiving 15 whole-life prison terms. The Court of Appeal judges rejected her appeals, and she has consistently maintained her innocence, with many supporters believing she was scapegoated for medical failings on the unit.
Since the convictions, numerous leading UK and international medical and scientific experts have challenged the prosecution's medical case, including Hindmarsh's evidence. Dr. Shoo Lee, a renowned Canadian neonatologist, led an expert panel that unanimously concluded the babies' deaths were due to natural causes and poor care, with no evidence of murders, insulin poisoning, or deliberate harm.
Letby's lawyer, Mark McDonald, applied to the Criminal Cases Review Commission (CCRC) to have her case reviewed, supported by reports from 27 leading experts, including Lee's panel. The CCRC is currently examining the application.
Hindmarsh appeared twice as a key witness for the prosecution during Letby's first trial, which lasted from October 2022 to August 2023, believed to be Britain's longest murder trial. As a professor and consultant paediatric endocrinologist with extensive clinical experience, Hindmarsh had worked at UCLH hospitals for decades and was an honorary consultant at Great Ormond Street.
However, Hindmarsh faced allegations at both hospitals that threatened his reputation and credibility in the months leading up to the trial. He was still employed at UCLH but no longer worked at Great Ormond Street, where his contract had been terminated four months earlier. The jury was never informed of these allegations or the formal investigation led by UCLH.
On November 15, 2022, Great Ormond Street referred 'multiple and wide-ranging concerns' about Hindmarsh's practice to the GMC, prompting a formal investigation. The same day, Hindmarsh testified for the first time at the trial. The tribunal imposed restrictions on Hindmarsh's work, citing the potential risk to the public and the impact on his ability to act as an expert witness.
Despite these concerns, Hindmarsh continued to provide expert testimony, and the tribunal allowed it, imposing the condition that he inform any party instructing him about the GMC investigation. This obligation is standard for expert witnesses, requiring them to disclose anything that might affect their credibility or impartiality.
The prosecution was not informed of the UCLH-led investigation until December 2022, suggesting they were not aware of it before Hindmarsh's first testimony. Hindmarsh formally informed the police about the GMC investigation on December 14, 2022, and the CPS waited two months before informing Letby's barrister about the investigation, which was disclosed just four days before Hindmarsh's second testimony.
The insulin evidence presented by Hindmarsh was particularly pivotal in the trial, with the judge instructing the jury that deliberate harm in one case could be inferred in others. However, experts challenging Letby's convictions have contested Hindmarsh's insulin evidence and the prosecution's case, arguing that the tests used to measure insulin are unreliable and that Hindmarsh's calculations are incorrect.
