Lucy Letby trial: evidence is ‘extremely tenuous’, says defence
Nurse’s barrister tells murder trial jury the research paper used by the prosecution as scientific evidence on air embolism is not a safe basis for conviction
Scientific evidence of how nurse Lucy Letby is said to have harmed several babies is so poor it cannot be safely used to support the allegations, the jury in her trial heard.
Closing speech in murder case focuses on quality of research into air embolisms
Ms Letby is accused of injecting air into the bloodstreams of a number of infants at the Countess of Chester Hospital’s neonatal unit. The prosecution said this caused air embolisms that blocked blood supply and led to sudden and unexpected collapses, with some proving fatal.
Ms Letby’s defence barrister Ben Myers KC used his closing speech at Manchester Crown Court on 27 June to ask the jury of eight women and four men to consider how the theory of air embolus worked in this case.
He said: ‘This is meant to be reliable, scientific medical theory, underpinning the most serious allegations. At the heart of it are prosecution experts – doctors Dewi Evans and Sandie Bohin. They are the ones we say are pushing it and the prosecution rely on it, of course. Neither of them has clinical experience in identifying or treating air embolus.’
As a basis for conviction, research paper is tenuous in the extreme, says nurse’s defence counsel
He said both witnesses had principally relied on a research paper about the effect of air embolism on infants, written more than 30 years ago, about the effect of air embolism on infants. The study showed 11% of 53 children had displayed signs of skin discolouration, said Mr Myers.
In several cases there were blanching and migrating areas of cutaneous pallor, the court heard, and in one case there was ‘bright pink vessels against a generally cyanosed cutaneous background’.
Mr Myers added: ‘As a basis for conviction for someone of murder and attempted murder, it is tenuous in the extreme. That meagre piece of research has carried into guesswork in this case.’
Counsel said both experts had identified five clinical features to support the identification of air embolus:
- Presence of an intravenous (IV) cannula.
- Sudden and unexpected collapse.
- Unusual skin discolouration.
- Presence of air in the great vessels of the heart.
- Unsuccessful resuscitation.
He added: ‘Apart from needing to have an IV entry point, we say not one of those criteria has been applied consistently… during this trial. [The experts] have chopped and changed them as much as required to fit the available evidence.’
Recollections of babies’ skin colour could have been ‘contaminated and influenced’
Mr Myers said there were many possible causes of discolouration in a baby and, in this case, there was no precise record taken, such as a photograph. The descriptions varied between witnesses, he said, and sometimes came months and years afterwards, following discussions with other witnesses.
Mr Myers added: ‘The dangers of recollection being contaminated and influenced are obvious.’
He told the jurors the number of babies in this case who recovered from alleged injection of air ‘does not make sense’ and that any neonate had potential to deteriorate suddenly and unexpectedly.
Air in the great vessels of the heart does not in itself diagnose a gas embolus, Mr Myers added.
Scientific evidence has been ‘applied inconsistently’
He said: ‘Scientific evidence needs to be sufficiently reliable if you are going to rely on it. What guidance you have had from the experts has been applied inconsistently throughout the case. The evidence is so poor it cannot be safely used to support these allegations.’
Ms Letby denies the murders of seven babies and the attempted murders of ten others between June 2015 and June 2016.
The trial continues.
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