The case against Lucy Letby was built on an array of circumstantial evidence – a convincing motive has never been identified.
So, as the Criminal Cases Review Commission considers submissions from Letby’s new defence team, here are the main questions about the prosecution case highlighted by her supporters:
1 – Why was Lucy Letby found guilty when no one witnessed her tampering with babies?
Letby was found guilty despite the absence of any direct evidence from witnesses, forensics, CCTV or post-mortems. The only medical witness at Letby’s two trials who seemed able to point to behaviour directly linking her to babies’ deaths was Dr Jayaram – but even his account has been called into serious doubt.
He testified that Letby was standing over Baby K’s cot as the girl was deteriorating and she did not call for help. But a recently unearthed email – which was not disclosed to her defence before the trials – appears to show she did call him for help. He wrote before she was investigated: ‘At time of deterioration . . . Staff nurse Letby at incubator and called Dr Jayaram to inform of low saturations [oxygen levels].’
2 – How convincing were the varied explanations for how Letby carried out her crimes?
Serial killers are notorious for having one modus operandi, which they perfect with chilling attention to detail. Yet the methods apparently employed by Letby seem more of a pick ’n’ mix of MOs. Variously, she was accused of injecting air into babies’ veins, forcing air into their stomachs, poisoning them with insulin, overfeeding them with milk and dislodging a feeding tube. Post-mortems of six of the suspicious deaths found five were due to natural causes, while one was unexplained.
Lucy Letby was sentenced to a total of 15 whole life terms last year
3 – How damning was a work rota presented to the jury which appeared to show Letby was present at all the deaths she was accused of?
Letby’s conviction leant heavily on the statistical likelihood of her being on duty at the time of 25 deaths and collapses. While 37 other nurses at the Countess of Chester Hospital were on duty for only a handful of cases each, a shift chart showed Letby was at the scene for them all.
However, it has since emerged from police notes that Dr Dewi Evans, the prosecution’s chief expert witness, originally looked at 28 cases of suspicious incidents – and Letby was absent for ten of them. The jury were not told about other deaths and collapses during the same period. Furthermore, door-swipe evidence in one case was wrong – showing Letby was on the ward when she wasn’t.
In September 2023, the Royal Statistical Society wrote to the chair of the Thirlwall Inquiry into the Letby case to warn that ‘it is far from straightforward to draw conclusions from suspicious clusters of deaths in a hospital setting’.
4 – How reliable was Dr Evans’s evidence?
Dr Evans, a 75-year-old former consultant paediatrician from Wales, provided the bedrock of evidence used to convict Letby. Over 30 years he had given expert evidence in criminal and civil cases on clinical negligence and child safeguarding – but had never specialised exclusively as a neonatologist.
Moreover, he had retired from frontline medicine in 2009. In response to an email submitted by this newspaper, he said he had not been responsible for the care of a premature baby since 2007.
During Letby’s trial the judge was given an unprecedented warning about Dr Evans issued by Appeal Court Judge Lord Justice Jackson, who argued that in a previous case Dr Evans had decided on the outcome he wanted before ‘working out an explanation’ to achieve it.
5 – Why did the police dispense with the services of the statistician who questioned their figures?
When the University of Warwick’s Professor Jane Hutton pointed out the flaws in building a case against Letby using the shift data, she was dropped by Cheshire Police. She has since said: ‘It is beyond reasonable doubt that this conviction is not safe.’
Letby’s (pictured during her arrest in 2018) conviction leant heavily on the statistical likelihood of her being on duty at the time of 25 deaths and collapses
6 – Did the prosecution understand the symptoms of an air embolism, one of the claimed methods of killing?
An air embolism occurs when gas bubbles enter a vein or artery blocking the passage of blood. They are very rare and the precise discolouration they cause to the skin is not widely known.
To buttress their assertion that Letby injected air into babies, causing such embolisms, the prosecution presented a 1989 study co-written by Dr Shoo Lee – a world-renowned expert on the condition. Yet the Canadian paediatrician was not called to give evidence and says his findings were misrepresented. Dr Lee has now undertaken a detailed study and proved air embolism as described by the prosecution experts simply could not happen. Following a full review of all the cases, 14 leading international experts assembled by Dr Lee said it was their joint opinion that no crime was committed.
7 – Did the fall in deaths after Letby was taken off duty prove her guilt?
Her supporters point to what they say is a more likely cause. The Countess of Chester neonatal unit was downgraded in 2016 so that it could no longer accept critically ill babies delivered at less than 32 weeks or in need of intensive care. This could easily have been the reason for the fall in deaths, not the removal of Letby.
In the same year, the Royal College of Paediatrics carried out a review into the spike in infant deaths and blamed unacceptable standards of neonatal care in the unit over a substantial period. It was deemed to be under-staffed and under-resourced.
8 – Did Letby really confess to murder on a Post-it note?
Much was made by the prosecution of incoherent therapy notes written by Letby after she first heard of the accusations, with one – ‘I am evil’ – said to amount to a confession. But taken as a whole they come across as an expression of guilt for failing to save ill children, not deliberately hastening their demise. Other notes read, ‘Why me? I haven’t done anything wrong’ and ‘I am not good enough to care for them’.
In 2016, the Royal College of Paediatrics carried out a review into the Countess of Chester Hospital neonatal unit’s spike in infant deaths and blamed unacceptable standards of neonatal care over a substantial period
9 – Were the internet searches carried out by Letby about the babies’ families as damning as they were presented?
The prosecution drew attention to the nurse’s online searches as a sign of a macabre fascination with their deaths. But it is not uncommon for nurses to look up patients or their families whose cases have affected them. With Letby, out of hundreds of searches, only some related to children harmed. There were also many babies in her care she did not search for.
10 – Why were nine prosecution witnesses (and the parents of the 17 babies) granted anonymity for life?
The identity of witnesses are protected if the judge deems their safety is at risk. But it is difficult to see the danger to the lives of witnesses in this particular case. Furthermore, it is highly unusual for the parents of victims to be given such anonymity. To many experts, it undermines the principle of open justice.
