The Lucy Letby trial, where the British nurse was found guilty of seven child murders and eight attempted murders in 2023, ignited a firestorm of public anguish and fury across the UK. Despite vehemently asserting her innocence and failing to appear for her sentencing, Letby was vilified as a coward on a public platform by then prime minister Rishi Sunak. However, amidst the wave of indignation, skepticism concerning the solidity of the evidence presented in her trial has begun to surface amongst experts.
Recently, a detailed piece in the New Yorker contesting the validity of Letby’s conviction was barred in the UK, owing to strict contempt of court laws. The censorship on UK reporting was lifted only after Letby was declared guilty earlier this month for attempting to murder another baby girl, referred to as Child K, a case where the initial jury couldn’t conclude.
Leading publications such as the Guardian and the Telegraph, as well as The Royal Statistical Society (RSS), have since indicated potential flaws in the trial procedure and expressed worries about the evidence used for Letby’s conviction. The RSS has also proclaimed that they are planning a review of the utilisation of evidence in courtrooms, prompted by concerns of members.
A sluggish acceptance of this raised eyebrow towards Letby’s trial can be attributed to some historical precedents. In the late 90s, Sally and Steve Clark experienced the personal tragedy of losing two infant sons to sudden infant death syndrome. Despite minimal evidence of any misconduct, Sally was wrongly accused of double infanticide. The prosecution’s prime witness, respected paediatrician Prof Sir Roy Meadow, proclaimed the chances of this misfortune being a coincidence as one in 73 million, and this statement was blasted across media platforms as irrefutable evidence of guilt. The rush to lay blame obscured the likelihood of Clark’s innocence that was later proved.
Clark’s case remains a stark reminder of how public perception can deviate from the truth. Significant statistical errors were identified in Meadow’s testimony, attracting censure from the RSS and British Medical Journal. Although Clark was cleared of charges in 2003, the irreversible damage was done and her life was tragically cut short in 2007 due to alcohol-related issues.
Not solely in Britain are miscarriages of justice a reality, with numerous women around the world finding themselves wrongly accused due to Dr. Meadow’s fallacious conclusions. A few notable cases include Dutch nurse, Lucia de Berk, who was wrongfully sentenced for the murder of seven patients back in 2003. However, she regained her freedom in 2010. Similarly, Daniela Poggiali from Italy, charged with 38 murders, reclaimed her innocence in 2021. Australian Kathleen Folbigg joined the list in 2023 after proving her non-involvement in the death of her four children, following a two-decade stint in prison.
All these convoluted cases lacked any direct evidence pointing to a crime having been committed. In each scenario, shoddy understanding of statistics and poor interpretation of clinical data led to the unjust verdicts. The case involving Letby did indeed exhibit striking resemblances to these instances, sparking fear amongst several experts. A significant piece of evidence used against Letby was a roster suggesting she was the only individual present during all the fatalities. Astonishingly, this listing failed to account for all neonatal deaths occurring at the unit, choosing only to mention those coinciding with Letby’s shift which inherently raises suspicion.
This misleading representation of events is fraught with the ‘Texas sharpshooter fallacy’, a term coined to describe the tendency to emphasise the commonalities within data while dismissing significant contrasts. This commonly happens when statistical findings are manipulated or misunderstood. To eradicate such deception, British courts implemented a guide governing the deployment of statistics and likelihoods in legal proceedings following the fiasco surrounding the Clark case.
Despite these measures, Letby’s trial raised eyebrows for the failure to adhere to this guide. This deviation stirred concern as the roster was allowed to serve as an exhibit, possibly inducing a wrongful assumption of guilt due to the lack of context provided. Such irregularities did not go unnoticed, as evidenced by figures like Richard Gill, a retired math professor from Leiden University in the Netherlands. He actively disputed the validity of Letby’s prosecution after playing a key role in the liberation of De Berk and Poggiali. His scepticism, aired through blog posts, caused a stir, leading to a warning for contempt of court.
Medical professionals have expressed serious reservations about the evidence underlying the conviction of Letby, who was accused of causing the death of children using diverse methods, including introducing air into their stomachs through nasogastric tubes, a point the prosecution made. This assertion, however, has been labelled as absurd, ludicrous and far-fetched by a panel of eight independent health experts engaged by The Guardian.
The prosecution in other instances posited that discolouration of the skin occurred due to air being injected directly into the veins. However, the remaining author of the paper used to support this claim confessed during Letby’s appeal hearing that his study had been misconstrued. The court deemed this clarifying testimony as inadmissible, contending that the defence should have dealt with it during the initial trial. In two additional instances where the children survived, it was suggested by the prosecution that Letby had covertly tampered with their insulin. However, various forensic scientists have disputed the prosecution’s forensic evidence presented as confirmation, calling it confusing.
The aforementioned issues neither prove nor negate Letby’s guilt, but they create sufficient doubt about whether the conviction can be confidently considered as surpassing the standard of beyond reasonable doubt.
It’s plausible that the UK police apprehended a remarkably clever and unique serial killer. Alternatively, the scepticism of experts implies another scenario: that a potentially innocent individual has once more been falsely accused of imaginary crimes by British law enforcement.
David Robert Grimes, an award-winning scientist and the author of The Irrational Ape: Why we fall for disinformation, conspiracy theory, and propaganda, is a recipient of the Nature/Sense about Science Maddox Prize and is also a member of the Committee for Skeptical Inquiry.