Three senior leaders at Lucy Letby's hospital have been arrested on suspicion of gross negligence manslaughter.
Detective Superintendent Paul Hughes, leading Operation Duet, said the arrests are part of a broader investigation launched in October 2023 after Lucy Letby's conviction.
That probe initially focused on corporate manslaughter and the hospital leadership’s response to rising infant deaths.
“In March 2025, the scope of the investigation widened to also include gross negligence manslaughter,” Mr Hughes said, noting that this offence targets “the grossly negligent action or inaction of individuals.”
The three individuals, who held leadership roles at the hospital in 2015–2016, have been bailed pending further enquiries.
Hughes stressed that “this does not impact on the convictions of Lucy Letby for multiple offences of murder and attempted murder.”
Investigations into both manslaughter offences – as well as deaths and non-fatal collapses at neonatal units in Chester and Liverpool between 2012 and 2016 – remain ongoing.
It comes as former Health Secretary Jeremy Hunt has called for Lucy Letby’s convictions to be re-examined in what is perhaps the biggest intervention in the child murder case yet.
Letby, from Hereford, was convicted of the murders of seven babies and the attempted murders of seven others, with two attempts on one child, when she worked on the neonatal unit at the Countess of Chester Hospital between June 2015 and June 2016.
After two trials, she is serving 15 whole-life orders, making her only the fourth woman in UK history to be told she will never be released from prison.
Mr Hunt, who was in post at the time of the murders, has called for her case to be re-examined, amid concerns the evidence used against her was weak.
Writing in the MailOnline, Mr Hunt said: “I was Health Secretary when many of the deaths attributed to Letby occurred at the Countess of Chester Hospital in Cheshire and, earlier this year, I gave evidence at the public inquiry set up to examine the issue.
“I agonised publicly over whether lessons from earlier scandals should have been learned more quickly, and apologised to families for any delays.
“So let me be clear from the outset: I am not arguing that Letby is innocent. That is not my place. I believe in the separation of powers. It must never be the role of any politician to second-guess the outcome of any court decision, let alone a jury trial.”
However, Mr Hunt does believe the case should be re-examined due to claims from experts there is no “medical evidence to support malfeasance causing death or injury in any of the 17 cases in the trial.”
“Taken together – and it pains me to say it – this analysis raises serious and credible questions about the evidence presented in court, the robustness of expert testimony and the interpretation of statistical data,” Mr Hunt added.
“That is why I and parliamentary colleagues such as Sir David Davis now believe the time has come for these concerns to be addressed as a matter of urgency…
“Re-examination of the evidence is not a denial of their pain. But it will ensure that all of us can have confidence that the truth has been reached through a rigorous and fair process.”
The Criminal Cases Review Commission (CCRC), which investigates potential miscarriages of justice, is considering evidence presented on her behalf from an international panel of medics who claim poor medical care and natural causes were the reasons for the babies collapsing.
Lawyers for the families of Letby's victims have dismissed the panel's conclusions as "full of analytical holes" and "a rehash" of the defence case heard at trial.
Letby, from Hereford, lost two bids last year to challenge her convictions at the Court of Appeal, in May for seven murders and seven attempted murders, and in October for the attempted murder of a baby girl which she was convicted of by a different jury at a retrial.
Cheshire Constabulary is continuing a review of deaths and non-fatal collapses of babies at the neonatal units of the Countess of Chester and Liverpool Women's Hospital during Letby's time as a nurse from 2012 to 2016.
A separate probe by the force into corporate manslaughter and gross negligence manslaughter at the Countess of Chester Hospital also remains ongoing.
