Was panel of consultants mistaken to solid doubt on Lucy Letby’s guilt? New medical reseach challenges their defence of killer nurse

New medical research has been published which casts serious doubt on claims of an expert panel that child killer Lucy Letby is innocent and the victim of a miscarriage of justice, the Daily Mail has learned.

The former neonatal nurse’s legal team have lodged reports from 26 medics, led by retired Canadian neonatologist Professor Shoo Lee, with the Criminal Cases Review Commission (CCRC), in a bid to get her free.

In a press conference last year, Prof Lee announced his panel of experts had concluded that medical evidence presented to convict Letby had been flawed.

He claimed that no murders had been committed and instead the seven babies Letby, 36, was found guilty of killing at the Countess of Chester Hospital, between June 2015 and June 2016, all died of natural causes or because of poor NHS care.

Prof Lee told journalists that his own research into air embolism – air bubbles in the blood – which was the method Letby used to kill – had been misinterpreted by the prosecution at her trial.

She couldn’t have injected the infants with air, Prof Lee insisted, because he had trawled the medical literature and failed to find a single case where venous air embolism – air in the veins – had caused a bright pink rash with bluish-purple skin, which, the trial heard, was seen on several of the infants who died.

Only arterial air embolism – air in the arteries – could cause the distinctive rash, which Prof Lee nicknamed the ‘Lee sign,’ he said.

But, the Daily Mail can reveal, new research published by a neonatologist in Taiwan as recently as October appears to contradict this claim.

And at least four other papers on air embolism, published between 1981 and the present day, have been missed, or wrongly interpreted, by Prof Lee, experts say.

The most recent paper, published in the journal Paediatrics and Neonatology last year, examines the case of a 33-week gestation premature baby boy who developed a blotchy purple and pink rash associated with air getting into their venous circulation.

The report, by Dr Shau Ru Ho, who works at the National Taiwan University Hospital, in Taipei, features striking photographs of skin discolouration on the infant’s arms and a video of an ultrasound scan, which ‘identified ubiquitous bubbles in the blood vessels’ of the infant’s brain, as well as in the inferior vena cava – the largest vein in the body.

‘The diagnosis was systemic air embolism,’ Dr Ho concluded.

It is understood the paper has also been sent to the CCRC, the body investigating Letby’s case as a potential miscarriage of justice, for consideration.

The Daily Mail has also spoken to an independent senior neonatologist, not involved in Letby’s trial, who said Prof Lee is incorrect to say that venous air embolism cannot lead to a similar blotchy skin rash or patchy discolouration.

Professor Paul Clarke, who works at Norfolk and Norwich University Hospitals NHS Trust, and is also an honorary professor at the University of East Anglia Medical School, said it is ‘entirely possible’ for air that is injected into a baby’s veins to end up in the arteries, or arterial circulation, via either a small hole between the right and left side of the heart, or a blood vessel that connects the pulmonary artery and the aorta. 

All babies are born with this hole and blood vessel, known as the foramen ovale and ductus arteriosus, which usually close naturally as they grow.

Prof Lee acknowledged the existence of the foramen ovale at the press conference but claimed it was impossible for air bubbles to pass through it because of higher pressure in the arterial system. He also claimed that any air injected into the veins would not reach the arterial system because it would be filtered out by small blood vessels in the lungs first.

However, Prof Clarke disputed Prof Lee’s assertions and said that the existence of cases in the literature proved that, if air is injected or accidentally enters a vein, air bubbles can pass through the hole in the heart or move via the blood vessel, mix with arterial blood and potentially manifest themselves as the ‘Lee sign’, which is caused when oxygenated blood passes through blood vessels in capillaries in the skin.

Speaking in a personal capacity, and not on behalf of his employers, Prof Clarke told the Daily Mail: ‘In my opinion it is a false dichotomy to claim that venous air embolism could never cause the arterial air embolism skin manifestations, including the supposedly specific but rare so-called ‘Lee sign’. The existence of cases in the literature is proof of this.’

The medic pointed to at least four other pieces of research into air embolism – not just the one published in October – which also appear to have been missed or misinterpreted by Prof Lee, who claims to have carried out two exhaustive reviews of the medical literature into air embolism, first in 1989, then in an updated report in 2024.

The papers include one written by an American paediatric neurologist in 1981, which described an almost immediate, but transient dark blue skin discoloration in a full-term baby boy after air was accidentally pumped into a vein in his scalp; another written by a South African neonatologist in 2003 which noted an infant with a venous catheter that developed ‘blue-black skin with blotchy red patches and extremely pale feet’ ; and one by an Israeli doctor, in 1996, which also described flitting skin mottling in a baby who had air mistakenly introduced into their circulation via an intravenous line in the foot.

Another piece of research, published by a medic based in Alabama, in 2007, which examined the case of an infant who died after air was accidentally introduced via a venous drip, was also very significant, Prof Clarke, said.

Even though no rash was cited in that baby, it provided ‘incontrovertible evidence’ that bubbles of air injected into a vein can work their way into, and be dispersed around, the arterial system because ‘collections’ of air were found in both veins and arteries after death.

‘The failure of Prof Lee to include the 1981 case in his original 1989 Lee and Tanswell paper, or the 1981 case and the 2007 paper in his subsequently updated research in 2024, are major omissions and show there has been a significant deficiency in his literature search strategy and selective publication,’ Prof Clarke said.

‘Both these cases provide clear-as-day evidence that venous air embolism can rapidly become arterial air embolism and so cause rapid onset skin rash.’

The 1996 and 2003 paper were included in Prof Lee’s research but have also been ‘misinterpreted,’ Prof Clarke said.

He also pointed out that the Israeli paper noted that air embolism was ‘exceedingly rare’ in premature babies and said that, over his 30-year career, he had only ever heard of one fatal case during his clinical practice, which occurred in the 1990s when a junior doctor forgot to flush the air from a venous catheter before it was inserted into a baby’s belly button.

Many of the doctors at the Countess of Chester Hospital told Letby’s trial that they had never seen such an unusual rash before or since.

Referring to the deaths of Babies A, D and E – infants murdered by Letby within a three-month period in summer 2015 – Prof Clarke added: ‘If three air-embolism deaths have occurred in such a short period of time in a single neonatal unit, that speaks for itself.’

Prof Lee told the Daily Mail: ‘The international expert panel of course welcomes scrutiny of our findings by those in the medical profession – however, respectfully, the interpretation of my paper in this instance is incorrect.’