Letby’s attacks escalated as she experimented with new methods for harming babies

Baby killer Lucy Letby became the poster girl for Babygrow Appeal, a fundraiser for the neonatal unit at Countess of Chester Hospital in 2013
Baby killer Lucy Letby became the poster girl for Babygrow Appeal, a fundraiser for the neonatal unit at Countess of Chester Hospital in 2013 - CHESTER STANDARD/SWNS.COM

Lucy Letby’s attacks on babies escalated as she experimented with new methods for harming children, the chief medical expert at her trial has said.

Dewi Evans said he believes that Britain’s worst child killer used a number of different techniques throughout her five-year career, some of which were almost impossible to detect.

On Monday, the Crown Prosecution Service will announce whether it intends to bring a fresh trial against Letby relating to six outstanding attempted murder charges which jurors were unable to reach a verdict on.

Dr Evans, a paediatrician, told the Sunday Telegraph he believed that prior to June 8 2015, when Letby murdered her first known victim, Baby A, the neonatal nurse’s preferred method was to remove or displace breathing tubes.

“For so many breathing tubes to come out, and they can come out accidentally, but for so many to come out over such a short period of time in what I consider to be a good neonatal department, that is very concerning.

“That method is extremely hard to detect, and prove. She changed her modus operandi over time.”

‘Foul play’

Dr Evans said that following Letby’s first arrest in 2018, he had been asked to review the notes of another 48 babies, who were not part of the trial, and he identified possible concerns with 18.

“I identified several cases in 2014 where tubes became displaced. None of those babies died or suffered long-term harm as far as I am aware.

“However, among those 18, there is also one death by insulin poisoning.

“It wouldn’t surprise me if she committed another insulin poisoning or two where doctors didn’t measure the insulin level after death.

“If you do not measure the insulin level then you can’t know whether there was foul play. There are undoubtedly more cases of insulin poisoning.

“Because these babies are so small it is really not that difficult to get away with causing them harm if you mix your methods and the children are on their own.”

Letby was convicted last month of murdering seven babies and attempting to murder six more at the Countess of Chester Hospital’s neonatal unit.

The 33-year-old became only the third woman alive to be handed a whole-life jail term.

Closing their arguments in the final days of her 10-month trial, prosecutors mentioned a previously unheard detail to the court.

‘The deaths really increased’

Two weeks before she murdered Baby A, Letby went on a training course which allowed her to administer medicine via special cannulas.

During the course, the potential dangers of air embolism was highlighted to her. From this point on, Dr Evans said, she began to inject air into her victims and the number of deaths on the unit rose significantly.

“As far as I am aware, there were no air embolism deaths before she went on that course. It was after she discovered that method, the deaths really increased”, he said.

According to CPS guidance, a decision on whether to seek a retrial will depend on the public interest.

The guidance states that “only cases involving significant public interest factors in favour of prosecution warrant a retrial”.

Earlier this month Letby also formally lodged a bid to challenge her convictions at the Court of Appeal.

Typically, applications for permission to appeal against a crown court decision are considered by a judge without a hearing.

If this is refused, people have the right to renew their bid for permission at a full court hearing before two or three judges.

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