The former boss of the hospital where Lucy Letby killed seven babies says she fears it is "more likely than not" that failures of management to deal with complaints about the nurse led to lives being lost needlessly.
Dr Susan Gilby joined the Countess of Chester Hospital as medical director and deputy chief executive in August 2018, a few weeks after Letby was arrested.
Letby, 33, was convicted of murdering seven infants and attempting to kill six others at the hospital's neonatal unit between June 2015 and June 2016. She will die in prison after being handed 14 whole-life orders.
Concerns about the serial killer were not addressed for months before she was finally taken off frontline duties and given a clerical role in June 2016.
Consultants who raised concerns about Letby as far back as 2015 have said babies could have been saved if hospital management had listened and acted sooner.
Both the neonatal unit head consultant, Dr Stephen Brearey, and another consultant Dr Ravi Jayaram have spoken of hospital executives' reluctance to involve the police for fear of damaging the trust's reputation. Officers were only contacted in 2017.
Speaking to Sky News, Dr Gilby said she commissioned a review and her "reflections on talking to the paediatricians, not just Steve and Ravi... and having looked at the evidence, is that there was certainly a possibility [that management failures to deal with complaints led to lives being needlessly lost]".
She added: "But it needs to be an external and objective review, looking at all the evidence, and giving people the right of reply to that evidence, that will come to that conclusion, and not for individuals such as myself.
"From a personal point of view, and obviously speaking more as a mother than a doctor or a senior leader in the NHS, it's my greatest fear and I think it's more likely than not that that will turn out to be the case.
"I sincerely hope that it isn't."
Dr Gilby also said there should be a full public inquiry, as per some parents' wishes, as a statutory inquiry "would have the powers to compel people to give evidence".
Dr Brearey first raised Letby's association with an increase in baby collapses in June 2015.
He told The Guardian that deaths could arguably have been avoided from as early as February 2016 if executives had "responded appropriately" to an urgent meeting request from concerned doctors.
Dr Jayaram continued to express concerns to management as more sudden and unexpected collapses followed.
Hospital staff 'certain' Letby would not be charged
Dr Gilby said that after she joined the hospital, there was "a very strongly held opinion, that appeared to me was held by everyone, that the police had made an error in arresting Letby".
"They were certain there would be no charges," she added. "And doctors who had persisted in raising concerns about Letby... were partly responsible for the arrest of a young woman who they had victimised and harassed over quite some time.
"I found that surprising because I knew that the police would have had substantial evidence that they would have wanted to put in front of her [Letby] if they seemed fit to make an arrest."
Detectives are continuing to review the care of 4,000 babies admitted to hospital while Letby was working as a neonatal nurse.
The period covers her spell at the Countess of Chester from January 2012 to the end of June 2016, and includes two work placements at Liverpool Women's Hospital in 2012 and 2015.
Dr Gilby said despite Letby's convictions and the end of the criminal trial at Manchester Crown Court "we're not quite at the point where we can really say there is closure".
She added: "The parents and others have questions about the circumstances around the events on the unit and how the crimes were allowed to go on for so long. So there is still a long road ahead in terms of getting answers to those questions."
Dr Gilby resigned as chief executive of the Countess of Chester Hospital NHS Foundation Trust in December 2022.
Jane Tomkinson, acting chief executive officer at the Countess of Chester Hospital NHS Foundation Trust, said: "Following the trial of former neonatal nurse Lucy Letby, the Trust welcomes the announcement of an independent inquiry by the Department of Health and Social Care.
"In addition, the trust will be supporting the ongoing investigation by Cheshire Police. Due to ongoing legal considerations, it would not be appropriate for the Trust to make any further comment at this time."
Sir Duncan Nichol, the former chairman of the NHS trust board, said he believed the board was "misled" in December 2016 when it received documents on the case.
"We were told explicitly that there was no criminal activity pointing to any one individual, when in truth the investigating neonatologist had stated that she had not had the time to complete the necessary in-depth case reviews. We were not given the full information we needed," he said.
He added that he has felt "strongly for a long time" that there must be an independent inquiry "to establish the true facts leading up to the police investigation and to hold to account anyone responsible for mistakes or delays".
Sir Duncan continued: "I am very pleased that one has been announced. No family should ever have to face what the loved ones of Lucy Letby's victims have endured. They deserve honest answers and the people of Chester deserve confidence that lessons have been learnt. I will do everything I can to support the Inquiry."