Lucy Letby: The killer nurse and the campaign to free her

Fallout from the case has triggered everything from calls for stronger protections for whistleblowers to the creation of a GMC-style regulator for NHS managers.

A statutory public inquiry is now in the pipeline to uncover what went wrong and how Letby escaped justice for so long despite colleagues repeatedly raising the alarm.

On the margins, however - mostly on social media - a very different view is taking shape.

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A fringe movement of amateur sleuths has already branded Letby's conviction as a miscarriage of justice and a US website, Science on Trial, is fundraising for an appeal so that the neonatal nurse "can have a fair trial where the evidence is reliable".

Letby was convicted by majority verdicts of 11-1 by a jury who sat through nine months of testimony. There was only one case - that of Baby Q - on which they were unable to reach a verdict.

Lucy Letby and the note described by the prosecution as a 'confession' of her crimes (Image: PA)

Yet some spectators remain confounded that this "dedicated" neonatal nurse - a fun-loving young woman with no obvious motive, evidence of personality disorder, or prior contact with police - should have embarked on her killing spree, seemingly overnight.

They borrow many of their arguments from the defence case, which it must be said the jurors have weighed up and rejected.

Facebook searches are one. It was presented as suspicious that Letby, now 33, had searched the social media site months and years after murdering some of the infants, looking up her victims' parents.

Letby's barrister, Ben Myers KC, pointed out that she had carried out more than 2,300 searches over the period covered by the charges: only 31 involved parents at the centre of the case; four affected families were never searched for at all; and she had also looked up parents of children she had cared for who were not involved in the trial.

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Evidence in support of air embolisms was "tenuous in the extreme", he said, with expert witnesses basing their testimonies on a single paper written by scientists in Canada in 1989.

Mr Myers noted that Letby had worked in the unit "for years" without incident until - over the space of a week in June 2015 - she had suddenly murdered two babies and tried to kill a third.

He argued that this did not make sense and laid the blame instead at changes in the unit itself, which had begun accepting a larger number of neonates with increasing complexity from 2015 onwards.

In this version, Letby was the scapegoat for wider problems. He detailed apparent errors in nearly all the infants' care, ranging from delays in administering antibiotics to ventilators set harmfully high.

After Letby was removed from the unit in June 2016, excess deaths and harms did return to expected levels - but around the same time the unit was downgraded, meaning it was no longer dealing with infants requiring intensive care. 

Kathleen Folbigg leaving Maitland Court in New South Wales, Australia after being refused bail on March 22 2004 (Image: Getty)

Beyond these claims, the Letby sceptics are drawing on everything from statistics to precedent.

In June this year, Kathleen Folbigg was freed from prison in Australia after serving 20 years for the murders of three of her children and the manslaughter of her son.

All four had died separately between 1989 and 1999, aged between 19 days and 19 months. Their mother was the only person at home or awake when they died.

Folbigg, now 55, consistently protested her innocence - insisting they had died from natural causes - but it was only when new evidence relating to genetic mutations came to light that she was finally pardoned.

More compelling for the "free Letby" lobby, however, are Folbigg's diary entries - submitted as evidence in her original trial - where she confessed to the killings in what are now accepted as symptoms of "maternal grief" and major depressive disorder, rather than admissions of guilt.

Comparisons have been drawn with Letby's own scribblings including a note - found in her home - where she had written: "I killed them on purpose because I'm not good enough".

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As for statistics, it was one of the central planks in the prosecution's case that Letby - and only Letby - was present in the unit when all the fatal or life-threatening collapses involved in the trial occurred.

It was this unsettling coincidence which first aroused consultants' suspicions.

But doubters warn of confirmation bias: that once Letby was in the line of fire, deaths which occurred while she was on duty automatically rang alarm bells.

What of the deaths which occurred when she was not on shift?

"How can you find out if the deaths that happened when Lucy was there are different from the deaths that happened when she wasn't there?," said Richard Gill, a retired professor of statistics.

Dutch nurse Lucia de Berk (L) leaves the court in Arnhem with her lawyer Stijn Franken (R) after her acquittal on April 14, 2010. De Berk, a 48-years old nurse, was sentenced to life imprisonment in 2004 for the murder of seven patients and the attempted murder of three others. (Image: Getty)

He successfully campaigned for the retrial of Dutch nurse, Lucia de Berk, who was famously convicted after jurors were told there was a "one in 342 million" chance that the string of patient deaths and resuscitations occurring on her shifts was down to random bad luck. 

She was exonerated in 2010 when a re-evaluation exposed statistical errors, weak medical evidence, and bias: in particular, investigators examining the incidents connected with De Berk "had classified deaths and resuscitations as suspicious when she was on duty, and not suspicious when she was off".

In 2022, Prof Gill co-authored a paper for the Royal Statistical Society with Neil Mackenzie KC - an Edinburgh based lawyer specialising in medical negligence - which warned that "seemingly improbable clusters of events can arise by chance without criminal behaviour".

Coincidence, they said, should never be ruled out without "convincing evidence to the contrary".