Police believe Lucy Letby, the nurse convicted of murdering seven babies, may have harmed dozens more infants at two hospitals in the north-west of England, the Guardian has been told.
A source with knowledge of the police investigation said detectives had identified about 30 babies who suffered “suspicious” incidents at the Countess of Chester hospital where she worked.
Letby, 33, has been found to be on duty for each of these unexplained collapses, it is understood. Police are also examining the medical records of babies born at Liverpool women’s hospital where Letby also worked.
These 30 babies, who all survived, are in addition to the 17 infants who featured in the nurse’s 10-month trial at Manchester crown court.
Letby is facing a whole-life sentence on Monday after being found guilty of murdering seven babies and trying to kill another six in “persistent, calculated and cold-blooded” attacks in the year to June 2016.
She was found not guilty of two counts of attempted murder and the jury was unable to decide whether she tried to kill another four.
Experts have been asked by Cheshire constabulary to examine the medical records of more than 4,000 babies born at Liverpool women’s hospital and the Countess of Chester between 2012 and 2015.
The Guardian has been told that the 17 babies who featured in the recently concluded trial were in “phase one” of the continuing police investigation, called Operation Hummingbird.
It is understood that detectives had earlier this year identified a further 40 babies who suffered “suspicious” incidents when Letby was on shift at the Countess of Chester hospital. Further inquiries meant that some of these infants were later de-prioritised by investigators, although their cases have not been dropped altogether.
By April, detectives are understood to have identified “suspicious” cases involving about 30 babies at the Chester hospital.
Investigations are also continuing at Liverpool women’s hospital, where Letby completed placements in 2012 and 2016. At least one family was told earlier this year by police that the birth of their child is part of the inquiry, it is understood.
Cheshire constabulary has said it is “impossible” to put a figure on the number of cases because the investigation, staffed by between 60 and 70 detectives, is still open.
Det Supt Paul Hughes, who led the Letby inquiry, has confirmed that there are “active investigations” into the collapses of “a number” of babies and that their families were being supported by specially trained officers.
He added: “From 2012 through to 2016, there were more than 4,000 admissions of babies into the neo-natal units of both the Countess of Chester hospital and the Liverpool women’s hospital for us to work through.
“This does not mean we are investigating all 4,000, it just means that we are committed to a thorough review of every admission from a medical perspective, to ensure that nothing is missed throughout the entirety of her employment as a nurse. Only those cases highlighted as concerning medically will be investigated further.”
Neonatologists are combing through the records of 4,000 babies and then passing to police any who suffered “unexpected and unexplained” deteriorations.
The police will then send those cases to the relevant hospitals to determine whether there may be an innocent explanation for the baby’s sudden collapse. If harm cannot be ruled out, that baby’s case will be examined in detail by medical experts instructed by Cheshire constabulary.
The scale and challenge of the investigation is huge, not least because of the number of babies involved and the time that has elapsed since they were born – but also because the medical evidence is incredibly complex.
The trial heard how Letby, who was in her mid-20s when she carried out the attacks, murdered newborns by injecting air into their tiny bodies, in some cases shattering their diaphragms, or in one case by pushing a tube down an infant’s throat. She tried to kill two babies by lacing their feeding bags with insulin.
Her victims included two identical triplet brothers, killed within 24 hours of each other, a newborn weighing less than 1kg (2lb) who was fatally injected with air, and a girl born 10 weeks premature who was murdered on the fourth attempt.
One of the babies was the size of an adult hand, weighing just over 535g (1lb), when she was born 15 weeks premature and given a 5% chance of survival. Letby tried to kill the girl twice – the first attempt just hours after she and the family had marked her 100th day of life with a celebratory cake, and the second on what would have been her due date two weeks later. Letby was found not guilty of a third count of attempted murder against her.
The little girl, known as Child G, was diagnosed with quadriplegic cerebral palsy after the attacks. Now eight, she is nil by mouth and requires 24-hour care.
Letby is expected to become only the third woman alive to be handed a whole-life tariff – meaning she will never be released from prison – when she is sentenced on Monday.
The other two women serving whole-life terms are Rose West, who tortured and killed at least nine young women in the 1970s and 1980s, and Joanna Dennehy, who murdered three men in what came to be known as the Peterborough Ditch Murders in 2013.
West, now 69, is believed to be serving her sentence at HMP New Hall in West Yorkshire, where Letby has been held since last October.
