Experts raise questions about medical evidence used to convict serial child killer nurse

Top scientists and doctors have raised concerns about how vital evidence was presented to the jury during the trial of a British serial child killer nurse.

Lucy Letby, 34, was sentenced last year to life in prison with no chance of release after being found guilty of murdering seven babies and the attempted murder of six others.

In July this year, at a second trial, the former neonatal nurse was convicted of attempting to murder another infant in her care.

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Now health and scientific experts have told the BBC they have concerns about how courts digest the complex medical evidence put before them.

Most of them did not attend the trials and they don't have an opinion on Letby's guilt but studied key medical evidence presented in court.

They have raised questions about the amount of insulin she required to harm babies in her care, the health condition of one of the babies she was convicted of murdering, and pathology analysis put to the jury.

During Letby's first trial, which ended last August, the court was presented with more than 100 days of complex evidence about the deaths at the Countess of Chester Hospital between June 2015 and June 2016.

This included prosecution allegations she killed two of her victims, described in court as Baby F and Baby L by adding a small dose of insulin to their intravenous feed bags.

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But New Zealand expert Geoff Chase told the BBC he calculated it would require 20 to 80 times the amount of insulin to prove fatal.

Letby was also found guilty of murdering another infant - Baby C - by deliberately pumping air into their stomach.

An X-ray taken on a day Letby was not working showed the infant had a swollen stomach.

But British neonatologist Michael Hall, who has previously expressed doubt about Letby's convictions, said there were '"a number of possible explanations" about excess gas being in the stomach of Baby C.

At Letby's first trial the pathologist for the prosecution told the court the death of Baby O, one of triplet brothers born in good condition, was due to an "impact injury" to his liver, similar to a road traffic crash.

But a top perinatal pathologist, who asked not to be identified, said she had observed this sort of liver damage at least three times in her career.

Every time time there were natural causes.

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Letby is serving 15 life terms with no chance of release — only the fourth woman in the UK to receive such a term.

But a growing number of supporters have raised doubts about the circumstantial and statistical evidence used against her.

This month an inquiry opened into how failures led babies to repeatedly be harmed at the Countess of Chester Hospital, how staff and management responded and how parents were treated.

But its head made it clear it would not be a review of Letby's conviction.

- With Associated Press