Two experts who previously supported Lucy Letby's claims of a miscarriage of justice have withdrawn their backing, stating that her barrister is jeopardizing her chances of freedom. Helen Shannon, a chemical engineering expert, and Geoff Chase, a professor of bioengineering, were part of an international panel that produced a report questioning Letby's convictions for the attempted murder of two infants.
In a statement to The Guardian, Shannon and Chase expressed concerns about the 'scientific credibility' and 'unresolvable problems' with certain aspects of the defense's evidence. They stated that while they stand by their assessment that the babies, identified as Baby F and Baby L in court, were unlikely to have been poisoned with insulin, they cannot support other arguments being used. According to the experts, these other arguments are 'inconsistent with the available evidence, science and established physiology.'
In a letter to the Criminal Cases Review Commission (CCRC), the pair wrote, "Whilst it is entirely legitimate for the defence to advance multiple arguments, some of the other arguments now being put forward we cannot support as scientifically credible and which have, in our view, fundamental unresolvable problems." They also accused Letby's barrister, Mark McDonald, of "placing the long-term interests of Ms Letby at serious, unnecessary and unacceptable risk."
Letby, 36, who maintains her innocence, is challenging her convictions for murdering seven infants and attempting to murder seven others at the Countess of Chester Hospital. She is currently serving 15 life sentences. The CCRC is reviewing a dossier of evidence submitted by an expert panel on her behalf. This panel, led by Canadian neonatologist Dr. Shoo Lee, previously suggested in February 2025 that the babies died of natural causes or due to poor care, rather than murder.
Shannon and Chase stated that continuing their association with arguments they believe are inaccurate creates a serious ethical issue under their professional codes and exposes them to sanction. They added that the consequences of the defense's strategy also extend to the families of the babies who died and were injured.
This development follows reports that McDonald has been referred to the Bar Standards Board over alleged professional misconduct. A formal complaint is believed to have been made by the families of Letby's victims, reportedly centering on a leaked letter from McDonald's solicitors to a coroner that allegedly included the protected names of some of the babies involved.
In response to the withdrawal of Shannon and Chase, McDonald stated that the case for Letby's innocence does not depend on any single expert. He asserted that the defense has gathered evidence from numerous international experts in insulin, endocrinology, and laboratory medicine, which he claims fundamentally undermines the scientific evidence presented at trial. McDonald added that the strength of this new evidence lies in its breadth and convergence, with independent experts identifying significant problems with the scientific basis used to convict Letby of poisoning the babies.
The CCRC, which has been reviewing Letby's convictions for 18 months, has declined to comment. A public inquiry into the murders is scheduled to publish its findings, which are expected to highlight missed opportunities for intervention by hospital management after concerns were raised about a spike in infant deaths in 2015 and 2016. A police investigation into potential corporate manslaughter and gross negligence manslaughter at the hospital is ongoing.