Peter Hindmarsh, a leading expert in pediatric endocrinology, gave key evidence in the trial of nurse Lucy Letby in November 2022 and February 2023, alleging that Letby deliberately injected insulin into the feeding bags of two newborns.[1][2] At the time of his evidence, Hindmarsh was under investigation by the General Medical Council (GMC) over concerns including the diagnosis and treatment of patients, the use of treatment in unusual age groups without adequate monitoring and cases where harm to patients was allegedly caused.[1][2] The GMC found that Hindmarsh may pose a "real risk" to the public and that his actions "may have the potential to affect his ability to act as an expert witness".[1] Great Ormond Street Hospital, where Hindmarsh was an honorary consultant, dismissed him from this position during his investigation.[1] Hindmarsh voluntarily struck himself off the GMC medical register in November 2024, with the investigation never ending.[2] A group of fourteen world-renowned experts later claimed that Hindmarsh's medical explanations at trial were incorrect and that they found no evidence that Letby had caused harm to any of the children she was convicted of.[1]