The results of a public inquiry into how Lucy Letby may have repeatedly killed and harmed babies will be published later on Tuesday.
The Thirlwall Inquiry was set up to investigate what happened at the Countess of Chester Hospital between 2015 and 2016 while Lethby was working as a nurse on the neonatal ward.
Letby, now 36, is serving 15 life sentences for killing seven children and attempting to kill seven more, including one child she tried to kill twice.
It was not the purpose of the inquiry to investigate Letby’s guilt. Instead, it examined how the hospital responded to concerns about the neonatal nurse and whether action could have been taken sooner to stop it.
Among the key questions the report may answer is whether any babies might have survived or avoided injury if action had been taken sooner.
Lethby was transferred from the neonatal unit to administrative work in July 2016 after consultants raised concerns about her with hospital management. But the investigation examined whether alarm bells should have started ringing earlier, such as in June 2015, after three babies died in a row.
The investigation, led by one of the country’s most senior judges, Lady Justice Thirlwall, required six months of evidence and thousands of documents worth more than £18.5 million.
The report is expected to highlight serious safety failings and recommend changes to the NHS.
The chair of the Criminal Cases Review Commission (CCRC) – the only body with the power to refer Lethby’s case back to the Court of Appeal – told the BBC the CCRC would be closely monitoring the report.
Lethby was twice previously refused permission to appeal his conviction.
Her lawyer Mark McDonald told BBC Newsnight on Monday that he had submitted to the CCRC “about 30 expert reports which really undermine the whole security of the convictions” – and that this was “more evidence” than “any other case” in the CCRC’s history.
He added: “If she is innocent, as I believe, as more than 30 experts believe, then everything that was done before the investigation and every recommendation was based on the wrong premise.”