How one of the UK's worst child killers went undetected

Before Lucy Letby's arrest and conviction, it took almost two years for the police to be called in over suspicious baby deaths at a Chester hospital

- Josh Halliday

In a discreet corner of a cafe in Chester, Dr Stephen Brearey recalls the exact moment he first connected Lucy Letby to a series of unusual baby deaths on the neonatal unit where they worked.

It was in a meeting with the hospital's head of nursing and two other colleagues on Thursday 2 July 2015. "It can't be Lucy. Not nice Lucy," he told them.

More than eight years later, 33-year-old "nice Lucy" will spend the rest of her life in prison after being found guilty of murdering seven babies and attempting to kill another six in crimes without parallel in modern Britain.

Through exclusive interviews, the uncovering of internal confidential documents, and months of reporting from Manchester crown court, the full story can be revealed of how concerns were raised about Letby for months before she was eventually removed from frontline care in July 2016. The failure of hospital executives to take urgent action cost the lives of at least two babies - two triplet brothers, murdered within 24 hours of each other - and prolonged Letby's attacks on other newborns at the Countess of Chester hospital in north-west England, senior doctors believe.

The decisions of executives will be investigated as part of a non-statutory public inquiry that will scrutinise what they knew and when and, crucially, why no investigation was ordered until July 2016 - more than a year after Letby's presence at a series of unexplained deaths was known. It will also examine why it took almost another year before executives spoke to the police.

Following Letby's conviction last Friday, detectives have begun contacting more families whose children they believe may have been harmed by the nurse. The investigation is examining the records of more than 4,000 babies born at the Countess of Chester hospital and Liverpool women's hospital in the six years to mid-2016.