Lucy Letby is the British nurse who was convicted of multiple counts of murder and attempted murder of neonates being cared for at the Countess of Chester Hospital. As our regular readers will know, our colleague Scott McLachlan was one of the first academics to raise serious concerns about the evidence used in the case, even well before it ever came to court.
He has published multiple detailed articles on his substack about the case. In the last year many more researchers and reporters have been raising their own concerns and, for reasons like those explained here, Scott’s pioneering work has not been properly recognised.
Scott has submitted a new paper about the case for publication and the preprint is available on ResearchGate (for those who cannot access ResearchGate the pdf is below). This paper is different to his other articles as it applies Bayesian reasoning to explain why it was inevitable that Lucy Letby would be found guilty of murdering several babies by a jury while at the same time likely being innocent.
The abstract:
In August 2023 British nurse Lucy Letby was convicted of multiple counts of murder and attempted murder of neonates being cared for at the Countess of Chester Hospital. In the sentencing statement, Justice Goss proclaimed Letby "cruel, calculating, cynical, deeply malevolent, a borderline sadist, absent remorse, and lacking of any mitigating factors". At that time a small group of academics questioned the quality and strength of evidence used to convict Letby. Revelations during her second trial, subsequent Thirlwall enquiry, and the recent Lee Expert Report have led even the main stream media to now question the safety of her convictions. This work uses Bayesian causal reasoning and two Bayesian networks (BNs) to understand the impact evidence has on the verdict and ask whether, on the basis of circumstantial evidence alone, it is possible that an innocent person could be found guilty of such appalling crimes. We show how Letby could simultaneously be innocent whilst having been found guilty of the crimes.
The paper can be downloaded here:
 | Letbymodelpaperv0 1.66MB ∙ PDF file |
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