The case against nurse Lucy Letby is weakening. Though she was convicted of killing seven babies and attempting to murder seven more, only one hospital staff member — consultant Dr Ravi Jayaram — claims to have seen her act suspiciously.

Jayaram’s testimony was key in both trials over the attempted murder of the infant known as Baby K. After the first jury failed to agree, Letby was convicted and sentenced to a whole life order for this crime last July. The central pillars of her other guilty verdicts are the claim that she was always present when babies died or collapsed unexpectedly, and medical evidence which has come under sustained attack from British and international experts, who say that none of the infants were deliberately harmed.

According to Jayaram’s testimony, when he walked into a room where Letby was alone with Baby K, he discovered that the infant’s oxygen levels had plummeted because her breathing tube had been dislodged, and that the nurse was standing over the baby’s cot without raising the alarm. “Lucy Letby was stood next to the incubator. She wasn’t looking at me. She didn’t have her hands in the incubator,” he told the court at her retrial.

Yet in an email seen by UnHerd, Jayaram initially suggested that, in fact, Letby had called him for help, and this was why he went to see Baby K. This was exculpatory evidence that could have helped Letby’s defence team, yet her lawyers were not told of its existence before either trial. It was not disclosed to them until late September last year.

Born at 25 weeks on 17 February 2016, Baby K struggled to breathe and was placed on a ventilator. Jayaram was first interviewed by police in September 2017 about the rise in neonatal deaths at Letby’s unit. He recalled checking on Baby K unprompted, saying: “I hadn’t walked in because I’d been called. I walked in just to check.”

On several further occasions, Jayaram repeated the claim that no one had warned him there was a problem before he entered Baby K’s room: in statements to police, in his courtroom evidence at Letby’s trials, and at the public inquiry chaired by Lady Justice Thirlwall, whose report is expected later this year. In one statement in 2018, he said that usually, when a baby’s oxygen level fell, a nurse would “come looking for a doctor to assist”, but Letby “had not called me in”.

Giving evidence at Letby’s re-trial, he said that when he was told that another nurse who had been looking after Baby K was going to leave her alone with Letby in order to speak to the infant’s parents, he became deeply concerned because “we had had a number of unusual incidents with babies” and he had “noted the association with Lucy Letby being present”. This made him feel “very uncomfortable”, which was why he went to check, finding Baby K was desaturating while Letby did nothing to help her. Prosecuting counsel Nick Johnson KC asked Jayaram: “Did you hear any call for help from Lucy Letby?” His answer: “No, not at all.”

The prosecution said that Letby had deliberately dislodged the breathing tube, and that Jayaram had caught her “virtually red-handed”. Later, at the Thirlwall Inquiry, Jayaram said he wished he had reported the incident at the time: “I lie awake thinking about this… I should have been braver.”

Yet in his first account of Baby K’s desaturation, Jayaram wrote that far from going to check Baby K because he felt uncomfortable that she was alone with Letby, the real reason was that Letby herself had raised the alarm and asked him for help.

He set this out in an email to seven of his colleagues dated 4 May 2017. Its timing was significant. The previous July, Letby had been moved to clerical work as a result of concerns raised by Jayaram and other doctors. But she had lodged a grievance for bullying and harassment, and this had been upheld. Now the doctors were hoping to involve the police, who at first had seemed reluctant. Jayaram was commenting on a draft of a report they would shortly send to detectives, asking them to investigate.

He was blunt about its purpose: “for the police to have their interest piqued”. To do this, he suggested, the doctors should “highlight explicitly for these cases that LL was in attendance and in close proximity to the incubators (in those situations we know for a fact she was)”. He went on to suggest additions to the report about cases with which he had been involved, “hopefully more in a stating the facts way than a subjective finger pointing way”.

Jayaram’s email described Baby K’s deterioration and suggested Letby called him about low oxygen levels — a detail that appears to conflict with his later testimony. After the other nurse left the room, he wrote: “Staff nurse Letby [was] at incubator and called Dr Jayaram to inform of low saturations.” He also wrote that the baby’s subsequent death was consistent with complications from extreme prematurity. The section in the email about Baby K was not included in the final report to the police.

Jayaram’s email was not disclosed to the defence before Letby’s trials. In other documents seen by UnHerd, Cheshire Police and the Crown Prosecution Service state that they only became aware of it in August 2024 — one month after Letby had been convicted of attempting to murder Baby K.

However, the documents say it was supplied to the Thirlwall Inquiry, but it was not discussed there nor published on its website. We asked the Inquiry whether it received the email before or after Letby’s retrial, but it refused to comment.

It was not until late September that Letby’s former defence team was finally sent the email by Operation Duet, the police inquiry into possible corporate or gross negligence manslaughter at the Chester hospital unit. We understand it will now be added to the dossier submitted by Letby’s lawyer Mark McDonald to the Criminal Cases Review Commission, which is being asked to refer the case back to the Court of Appeal.

Jayaram did not respond to a request for comment. A Countess of Chester Hospital spokesperson told UnHerd: “Due to the Thirlwall Inquiry and ongoing police investigations, it would not be appropriate to comment further at this time.”