Expert witness in Lucy Letby trial did not reveal hospital investigation into his medical work

The police force behind the prosecution of the former nurse Lucy Letby has said it was not informed by a key expert witness before he gave evidence at her trial that he was under investigation over serious concerns in his medical work.The Crown Prosecution Service also told the Guardian it was not aware that Prof Peter Hindmarsh was subject to the formal investigation by the hospital that employed him, before his first appearance as a witness on 25 November 2022.Hindmarsh provided crucial evidence in the trial for the prosecution’s case that Letby had attempted to murder two babies, referred to as F and L, by injecting insulin into their fluid bags.The Guardian revealed last week that in the period leading up to the trial University College London hospitals NHS trust (UCLH), Hindmarsh’s main employer, was leading a formal investigation, with involvement from Great Ormond Street hospital, into multiple, wide-ranging, serious concerns, including allegations that Hindmarsh harmed patients.Rules governing criminal cases require expert witnesses to disclose to the side they are giving evidence for – in Hindmarsh’s case Cheshire police – anything “that might reasonably be thought capable of undermining the expert’s opinion or detract from the credibility or impartiality of the expert”.Senior lawyers have told the Guardian that these duties of disclosure can include investigations by an expert’s employer, like the one into Hindmarsh’s professional conduct.Glyn Maddocks KC, joint secretary of the all party parliamentary group on miscarriages of justice, said: “As I understand the rules, in order to be open and transparent with the court, this expert should have disclosed this investigation, so that its relevance and importance could be assessed. It’s vitally important that the integrity of experts is retained at all times.”Tim Green KC, a barrister experienced in the disclosure rules, said he could not comment on the details of the Letby case, but in general, an expert would be expected to disclose an internal investigation by his employer, particularly if it had reached an adverse conclusion.“If the investigation report was critical of an expert’s competence and skill, I would expect a physician who had experience in giving expert evidence to disclose the trust’s investigation into him/her to those lawyers seeking his opinion. That is to enable the instructing lawyers to ensure the expert complies with the disclosure rules before he gives evidence.”Hindmarsh contract terminated before trialLetby was convicted of murdering seven babies and attempting to murder seven others in the neonatal unit of the Countess of Chester hospital, over two trials in 2023 and 2024.The two insulin cases were pivotal in Letby’s conviction and were two of only three guilty verdicts on which the jury was unanimous.The former nurse has always maintained she is innocent. In February last year, her lawyer Mark McDonald submitted an application to the Criminal Cases Review Commission that the convictions were unsafe and should be referred back to the court of appeal.The CCRC is reviewing the application, which is supported by reports from 27 experts, including a panel of leading UK and international doctors led by the Canadian neonatologist Dr Shoo Lee. They say the prosecution’s medical evidence, including Hindmarsh’s, was wrong, that the babies died from natural causes and poor care on the unit, and there was no evidence of any murders, insulin poisoning or any other deliberate harm.Hindmarsh was one of eight expert witnesses for the prosecution. He was an eminent figure in British medical practice; a consultant paediatric endocrinologist – specialist in hormones – and clinical director for paediatrics (child medicine) at University College London hospital. He was also an honorary consultant, working at Great Ormond Street, the world-famous children’s hospital.However, his contract was terminated by the hospital in July 2022, four months before he gave evidence at the trial. Cheshire police confirmed that Hindmarsh also did not disclose this to the force.When he appeared as an expert witness for the first time in November 2022, Hindmarsh was asked by Nick Johnson KC, lead barrister for the CPS, whether he was an honorary consultant at Great Ormond Street. Hindmarsh did not make it clear that his contract had been terminated.‘No disclosure until December 2022’Ultimately Great Ormond Street referred its concerns about Hindmarsh to the regulator, the General Medical Council. The GMC opened an investigation into Hindmarsh’s fitness to practise on 25 November 2022, the same day he first gave evidence for the prosecution of Letby. UCLH then also reported its concerns to the GMC.Great Ormond Street informed Hindmarsh of the referral on 30 November 2022. Hindmarsh did then disclose to the Cheshire police, on 14 December 2022, that he was under investigation by the GMC. Both the police and CPS told the Guardian that was the first disclosure he had made. The jury at the trial was never told of the investigations.The allegations against Hindmarsh were never finally adjudicated, because in November 2024 he removed himself from the GMC register of doctors, a process known as “voluntary erasure”.A spokesperson for Cheshire police said: “The professor made a disclosure to Cheshire police in December 2022 and we then notified the CPS.”A CPS spokesperson said: “We can confirm we are not aware of any disclosure being made by Prof Hindmarsh to the police until December 2022.”McDonald said he would now be submitting Hindmarsh’s non-disclosure of the hospitals’ investigation into him as further evidence in support of the CCRC application.“Given the importance of Prof Hindmarsh’s evidence, I am astonished that he did not disclose, before he gave evidence, that his contract at Great Ormond Street had been terminated and that he was under investigation. His failure to disclose these matters in itself raises questions over his credibility and integrity.”In response to questions from the Guardian about his disclosure, a representative for Hindmarsh said: “We have no comment at this time.”