In this episode Caroline and Liz have the evidence of former Detective Chief Superintendent Nigel Wenham, the police officer who was instrumental in launching the police investigation into Lucy Letby’s crimes.

They also hear from one of the key doctors in the case - Dr Stephen Brearey - the lead consultant on the neo-natal unit. He apologised to the families of the babies murdered and harmed by Lucy Letby, saying he tried to do his best to protect their children but admitted his best was not good enough.

He said the pressures of his day job in the NHS meant he was too busy to properly review cases of babies who collapsed and died and he failed to spot she was harming patients sooner.

He also revealed that he now believes Lucy Letby had killed other children on his unit for some time before she killed Baby A - the first of seven babies she was convicted of murdering - in June 2015.

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