Questions about the safety of Lucy Letby's convictions continue to mount, as new concerns emerge about the handling of the case by Cheshire Police and the Crown Prosecution Service. Letby, a former nurse, was found guilty of murdering seven babies and attempting to murder seven others at the Countess of Chester Hospital. Her new barrister, Mark McDonald, is preparing an application to the Criminal Cases Review Commission, supported by leading neonatologists who argue there are plausible alternative causes for the babies' deaths.
At the centre of criticism is the use of a shift chart during Letby's first trial, which showed which nurses were on duty when babies allegedly were attacked. Leading statisticians have described it as a classic example of the 'prosecutor's fallacy', where a case is built to support a suspicion rather than exploring all possible explanations. Professor Jane Hutton of the University of Warwick stated: 'It's a large pile of crockery, much of which is broken. Such a pile does not hold water, however big it is.'
Documents reveal that the police investigation was initially based on statistical coincidence. In May 2017, seven doctors compiled a report noting Letby's presence at 11 deaths, saying the likelihood of this occurring by chance alone was 'very low'. However, hospital managers stated that when they approached police, it was explained there was a 'high statistical relationship' but no other evidence. Assistant Chief Constable Darren Martland acknowledged the lack of a specific criminal allegation.
Cheshire Police initially engaged Professor Hutton in 2018, asking her to calculate the probability of one staff member being on duty during all deaths. She advised that a proper statistical inquiry should consider all possible explanations, including medical conditions and unit performance. Despite her advice, the police proceeded with their investigation, leading to Letby's conviction. The Thirlwall inquiry continues to examine the case, though its chair has warned against 'noise' questioning the verdicts.
