Initial investigation

An informal review conducted in June 2015 by a consultant and lead neonatologist at the Countess of Chester Hospital NHS Foundation Trust revealed troubling details regarding four unexplained collapses that occurred in the same unit. Three of these cases resulted in deaths in the same month. It was observed that Letby had been on shift on each occasion. The unit's consultants promptly reported these deaths to the trust's committee responsible for addressing serious incidents. The committee classified the deaths as "medication errors". Had they been classified as "serious incident[s] involving unexpected deaths", an immediate investigation could have taken place if they were grouped together.^[6] The numbers of unexplained collapses were particularly abnormal: there had previously been only two or three deaths a year in the neonatal unit. What was also particularly unusual was that the babies did not respond to resuscitation attempts as they would be expected to.^[3]: 23:40 Usually babies that had got a heartbeat back would see an improvement in their breathing, but that did not happen in these cases.^[3]: 23:45 Detective Superintendent Paul Hughes, who later led the investigation,^[13] was told by two medical consultants that baby collapses which occurred during the spike had been unexpected and could not be explained, both of which were not usual with infant collapses in general.^[14]

In October 2015, a ward manager conducted her own review, noting that Letby was the only staff member consistently present throughout these incidents of unexplained collapses and deaths. These findings were relayed to the lead neonatologist. Further concerns were voiced to management by the unit's consultants that same month; concerns were either resisted by the Trust Executives or ignored.^[9][15] In February 2016, the lead neonatologist, along with other consultants, concluded a thematic review investigating five unexplained deaths and collapses within the unit. Their investigation determined that the only common factor in these cases was the presence of Letby. The lead neonatologist contacted the unit manager, the hospital's medical director and the director of nursing, requesting an urgent meeting.^[15] A meeting took place in May 2016.^[16] The executive team deemed the spike in deaths to be coincidental and no substantial action was taken.^[6][16]

Reports by the Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the UK project (MBRRACE-UK) found a neonatal death rate at least 10% higher than expected between June 2015 and June 2016. Additionally, the neonatal death total in 2015 doubled that of the previous year.^[17][18][19] The mortality rate had risen above what might be considered 'normal' rates.^[20] During a hospital visit in February 2016, The Care Quality Commission (CQC) was informed of difficulties in raising concerns with managers, but heard no mention of an elevated mortality rate. The CQC's report identified issues of "short-staffing" and "skill-mix" issues within the unit, yet it praised the overall positive culture of the trust, where "[s]taff felt well supported, able to raise concerns and develop professionally."^[9]

On 24 June 2016, following the deaths of two triplet babies on that day and the previous day, the lead neonatologist phoned the duty executive demanding that Letby be removed from the unit. The duty executive insisted that Letby was safe to work and that she was "happy to take responsibility" if anything happened to any more babies under Letby's care.^[16][15] In late June 2016, the trust's executive directors convened to address the question whether to involve law enforcement. By this time, seven unexpected deaths had taken place within the unit. The belief among these executives was that the indications of Letby's involvement were largely circumstantial and they suspected certain doctors of embarking on a misguided "witch hunt". Moreover, they were concerned about potential harm to the Trust's reputation resulting from a police inquiry. Ultimately, they opted against engaging the police.^[6] The medical director and chief executive instead organised a review through the Royal College of Paediatrics and Child Health (RCPCH), which was initiated in September 2016. At the same time, the unit's services were scaled back in July 2016,^[6] no longer accommodating premature births before the 32-week mark. Such cases were redirected to other hospitals in the North West of England, such as Alder Hey Children's Hospital.^[21]

The trust set a narrow scope for the review that excluded investigating Letby's actions or the deaths, but instead focused on the unit's general service. The RCPCH reported their findings to the medical director and chief executive in October 2016.^[6] They could not find a definitive explanation for the increase in mortality rate at the unit but found some insufficient staffing and senior cover. The report recommended a detailed case review of each death. The medical director asked neonatologist Jane Hawdon from Great Ormond Street Hospital to carry out the case reviews. Hawdon responded she could not conduct a detailed review because of lack of time but could provide a summary and did so after briefly reviewing the notes. She identified four cases that "potentially benefit from local forensic review as to circumstances, personnel etc".^[6][9][22] The board's chair at the time, has said that he was misled about the scope of that review and its findings.^[23] Despite the thorough external independent review recommended by the RCPCH or the forensic review recommended by Hawdon, records of the hospital board meeting show the medical director telling board members that the RCPCH and Hawdon reviews concluded that the deaths in the neonatal unit were due to issues with leadership and timely intervention.^[15]

In September 2016, Letby raised a formal grievance about her late June 2016 transfer from clinical duties to the hospital's risk and patient safety office.^[15] This grievance was upheld by the board in January 2017, which determined her removal had been "orchestrated by the consultants with no hard evidence". They supported her return to the neonatal unit and offered her a placement at Alder Hey Children's Hospital in Liverpool plus support to develop advanced practice or a master's degree. The medical director also commented in the report that the trust's intention was to "protect Lucy Letby from these allegations".^[6][9][24] The chief executive had met with Letby and her parents on 22 December 2016 to apologise on behalf of the trust and assure them that the doctors who made the allegations would be "dealt with".^[6] He later ordered the consultants to send a letter of apology to Letby, which they did in February 2017.^[24][13]

In March 2017, consultants asked management to involve the police after receiving advice from the regional neonatal lead, who suggested further investigation was needed.^[9] They then met with Cheshire Constabulary on 27 April 2017, to raise their concerns, with Letby due to return to work on 3 May 2017.^[13] The trust publicly announced the involvement of the police in May 2017, stating this move was to "seek assurances that enable us to rule out unnatural causes of death."^[9][25] The police's investigation was called Operation Hummingbird.^[26] Senior Investigating Officer Paul Hughes later said: "the initial focus was around the hypotheses of what could have occurred: so generic hypotheses of 'it could be natural-occurring deaths', 'it could be natural-occurring collapses', 'it could be an organic reason', 'it could be a virus', and then one of the hypotheses was that, obviously, it could be inflicted harm."^[20]

Timeline of cases

The first suspicious case occurred on 8 June 2015.^[20] At 8 pm a healthy baby boy – a twin – was being cared for in nursery 1 on the ward and the designated nurse was Letby.^[20][27] The boy had been handed over to Letby after she started her night shift, with the paediatric registrar having clocked off when Letby was 30 minutes into her shift.^[20][27][28] Twenty-six minutes later, she called a doctor with the baby's state rapidly deteriorating. The baby died half an hour later, less than 90 minutes into Letby's shift.^[20] The paediatric registrar later testified that when she heard about the death of the child the next day after returning to work that it was a "big surprise" and "completely out of the blue and very upsetting. [He] showed no signs of any problems throughout the day. He was handling well. I had no concerns at all for him or his twin sister".^[28] A fellow nurse said that when the baby started deteriorating she saw Letby standing over the infant's incubator and originally did not intervene. However, the nurse then did when she realised he was not recovering under Letby's care.^[28] Doctors attending the scene said that Child A developed an unusual blue and white mottling on his skin after collapsing, which they said they had never seen before.^[29] This symptom later occurred in other babies that were believed to have been intentionally injected with air.^[29] The day after Child A's death, Letby searched for his parents on Facebook.^[29]

About 28 hours after Child A's death, his twin sister, Child B, also collapsed and had to be resuscitated.^[27] After Child A's death, the parents had spent the day with Child B in the nursery with her, but were persuaded to go and rest before the baby's sudden crash.^[29] Tests later showed loops of gas-filled bowel in the child.^[27] As a result, it was later concluded that the baby had been injected with air.^[27] Letby had fed the baby 25 minutes before their collapse and the child had the same unusual rash on her skin as first seen on Child A hours earlier, indicating that they had also been injected with air.^[29]

A few days later, Child C, a boy in good condition, died.^[27] He suddenly collapsed as soon as another nurse left the nursery.^[29] Despite not being the designated nurse for the child, Letby was witnessed standing over his monitor as his alarm sounded when the other nurse came back in.^[27][29] Letby's shift leader had already told her to focus on her designated patient and the shift leader later testified that she had to keep pulling her away from the family room as Child C died.^[29] His parents later recalled a nurse they believe was Letby brought a ventilator basket in and said, even though their child was not dead, "You've said your goodbyes, do you want me to put him in here?".^[30]

On 22 June 2015, baby girl Child D collapsed three times in the early hours and died.^[27] Those who attempted to save the child noticed the girl's skin had been discoloured.^[27] A post-mortem X-ray showed a 'striking' line of gas in front of the spine, consistent with air being injected into the bloodstream.^[31] A doctor later testified that such a finding could not be explained by natural causes.^[32] The mother had noted Letby "hovering around" the family hours before the baby collapsed.^[29]

On 2 July, a doctor raised his concerns over the sudden collapses and deaths.^[27] No action was taken against Letby.^[27] At about 9 pm on 3 August, the mother of Child E, who had come to the neonatal unit to give him and twin Child F her expressed breast milk, rushed into the room of Child E, having been alarmed by a scream. She found the child having fresh blood around the mouth and being in extreme distress. Letby, standing near^[33] to his incubator, was described by the mother as "not doing anything" in the face of the apparent emergency.^[3]: 3:30 The mother would recount seeing Letby then as someone who "wants to look busy but they're not actually doing anything".^[3]: 3:30 Letby said that the bleeding had merely been from a rubbing feeding tube and asked the mother to calm down.^[33] The boy died in the early hours of 4 August after having lost about a quarter of his blood, a "striking" amount according to a blood specialist testifying at court, who agreed with defence that her observations did not help establish a cause of death; injection of air was another suspected reason for the death.^[27][34] Flecks of blood were found in his vomit.^[35] No post-mortem was carried out.^[36] The next evening, Child E's twin brother Child F was being cared for in nursery 2, the same room in which Letby was looking after another infant.^[20][27] At 1:54 am Child F suffered an unexpected drop in his blood sugar and saw a surge in his heart rate.^[20] The child survived and a blood test later revealed that he had been given an "extremely high" amount of exogenous pharmaceutical insulin, which he had never needed.^[20][27] No baby on the unit had been prescribed insulin at the time and so there was no reason why this baby should be given it.^[20] The insulin was kept in a locked fridge next to a nurses' station.^[20] Later, at trial, Letby did not contest that the baby had been intentionally injected with insulin, suggesting someone else must have done it.^[29] Letby searched for the parents of Child E and F on social media in the following weeks and months, and for other parents who were not part of the case.^[37][38]

On 7 September 2015, Child G, on her 100th day of being alive, collapsed for the first of three times in the following three weeks.^[27] After the first collapse, the baby girl was taken to Arrowe Park Hospital, but five days later she collapsed again, 15 minutes after Letby had been feeding her.^[27] The child survived, but is now severely disabled as a result of what happened to her.^[27] The baby was witnessed projectile vomiting so massively that it reached the chair next to the cot and canopy.^[39] Her heart rate and oxygen levels also dropped to unusually low levels.^[39] Later, at trial, an expert witness doctor concluded that the only viable explanation for the baby vomiting so extraordinarily was if she had received far more milk than that allocated down her feeding tube and that this could not happen accidentally.^[39] It was later discovered that Letby had deliberately altered the baby's temperature on her observation chart to make it seem like she was already unwell before she collapsed, and also falsified the time of the baby's collapse to make it seem like it coincided with when a colleague gave the baby a milk feed.^[29] A nurse noticed when she arrived after Letby's cry for help after one of the baby girl's collapses that the machine connected to the baby to measure its oxygen saturations and heart rate levels had been turned off.^[29] The nurse stated in court that two doctors had apologized to her for not having the machine switched back on after fitting a cannula to the baby girl. One of the doctors concerned told the court that he did not remember the apology but considered it possible that it had taken place. He agreed that leaving the monitor switched off was "not normal protocol" and possibly a result of his having to rush to another emergency.^[40] A colleague had also noticed that Child G's initial collapse occurred on the day she was originally due to be born.^[41]

About six weeks after Child G's multiple collapses, on 23 October 2015, Child I died.^[27] This was the fourth time the baby girl had collapsed.^[27] On the fourth collapse, Letby was found next to her incubator by another nurse.^[42] Letby later sent a sympathy card to the baby girl's parents on the day of her funeral, a card which Letby kept photos of on her phone.^[27][20][43] Letby also wanted to go to the funeral.^[44] Twice the baby was found to have excess air in her stomach which had affected her breathing.^[42] Before the second collapse, Letby had said to a colleague that Child I 'looked pale', even though it would have been hard to see from where they were standing in a doorway looking into the darkened nursery.^[29] Then, when the designated nurse for the child turned the light on, she saw the girl was not breathing.^[42] The child's mother later said Letby 'smiled' as she bathed her dead daughter and offered to take a photo of the dead child.^[29][45] A doctor had seen unusual skin mottling on Child I's skin and X-rays showed the child had a massively enlarged stomach that was consistent with her having been deliberately injected with air.^[46][47] Letby later searched for Child I's mother on Facebook.^[45]

Later on 23 October, the hospital management was alerted to the concerns of the doctors on the unit.^[27] They were told to "not make a fuss".^[27] Staff reviews were carried out which highlighted that Letby was always on duty for the suspicious incidents and in February 2016 a doctor requested an "urgent" meeting with executives, but no meeting occurred until May 2016.^[27]

By April 2016, Letby had been moved to day shifts because of the concerns about her and the suspicious collapses began occurring in the daytime.^[29] On 9 April 2016, two twin brothers suffered sudden collapses within hours of each other.^[27] Tests found that Child L had insulin levels in his blood "at the very top of the scale that the equipment was capable of measuring".^[27] Hours later, twin brother Child M's heart rate and breathing suddenly dropped and he nearly died.^[27] Experts said that Child M's heart problems were likely to have been caused by air being injected into his bloodstream.^{[48][48]: 3:00} Although he lived, the child suffers from brain damage.^[27] It was noted that the collapses of Child L and M occurred in almost identical circumstances to Child E and F.^[29] Both were twins where one was believed to have been injected with insulin and the other with air.^[29] Child F had survived his injection of insulin and it was noted that Child L had been injected with twice the dose of insulin, the suggestion being that Letby had done so to ensure death on this occasion.^[29]

A meeting about the suspicious cases took place on 11 May 2016, but no action was taken.^[27]

A month later, Child N nearly died after suffering trauma to the throat.^[27] Doctors saw blood and "unusual" swelling at the back of his throat upon examination.^[49] The baby had been heard randomly "screaming", the jury was told.^[50] Child N's father said he then saw blood spattered around his son's mouth.^[51]

The final two cases occurred within hours of each other on 23 and 24 June 2016.^[27] The two children involved were triplets, siblings of each other, and the cases occurred on Letby's first shift back after a holiday in Ibiza.^[29][27][52] Child O, a "perfect" healthy baby, was due to be discharged home, but suddenly collapsed on 23 June.^[27] When the child initially became unwell, another nurse suggested he be moved to nursery 1 where the sickest children were treated, but Letby disagreed and the baby subsequently collapsed less than two hours later.^[20] He recovered, but suffered two further collapses and died almost exactly three hours later.^[20] The lead consultant noted that the child "should have responded better" to resuscitation.^[20] X-rays on a post-mortem showed he had an abnormal amount of gas in his body and liver damage that an independent pathologist later ruled had resulted from an "impact injury" similar to what would be seen in a car crash.^[29][27] 13 minutes after Child O's death, Letby was feeding his triplet brother Child P, who also was expected to be able to soon go home, but he collapsed after his diaphragm was somehow shattered.^{[27][48]: 4:40} Doctors believed he would make a full recovery. As they prepared him to go to another hospital, Letby said: "He's not leaving here alive, is he?".^[27] The boy soon died.^[27] X-rays likewise showed an inexplicable amount of gas inside the baby.^[53] These deaths have been described as "exceptional" and the "tipping point" when the consultants realised that "drastic" action needed to be taken.^{[48]: 4:40 [48]: 12:35} A consultant allowed the surviving triplet to be taken to a different hospital by medics who had turned up to take Child P.^[29] The consultant said she allowed this after her parents begged for it, as she now felt Letby was a "mortal danger" to the surviving triplet.^[29] Before the second triplet died, Letby had texted a doctor saying she would "be watching them both [Child P and the surviving triplet] like a hawk" and said "I'm OK. Just don't want to be here really. Hoping I may get the new admissions".^[53]

Towards the end of June 2016, Letby was removed from the neo-natal ward^[3]: 29:00 and instead moved to a clerical role within the hospital,^[54] and the suspicious collapses stopped.^[3]: 29:00

Prosecutions, trials and convictions

Motives

During Letby's trial, the prosecution suggested several possible motives for the killings including boredom, that she "got a thrill" from the events surrounding the deaths and that she enjoyed "playing God". The prosecution told the jury that "[s]he was controlling things. She was enjoying what was going on. She was predicting things that she knew was going to happen." Another possible motivation suggested by the prosecution was that the killings were to gain the attention of a married doctor with whom Letby allegedly had a secret relationship. She had texted this doctor 'non-stop' during some night shifts, minutes before attacking babies.^[3]: 14:30 One sheet of paper found in Letby's office and shown to the court was an annual leave form, on which Letby had written phrases including, "I trusted you with everything and loved you", "you were my best friend" and "please help me".^[119] The doctor was one of those called when a baby rapidly deteriorated. Letby denied all these suggestions, including the allegation that she had a relationship with the married doctor.^[120] During her trial it was noted that Letby broke down for the first time only when this doctor who she allegedly had a crush on gave evidence and she tried to leave the dock without permission at this point.^{[75]: 14:30} When questioned why she did this Letby said she had "felt unwell" and when questioned, she claimed she "didn't know" what 'go commando' meant, even though the doctor she allegedly fancied had sent it to her in an apparently flirtatious text, to which she replied to with laughing emojis.^[121]

The Guardian, in its reporting after the verdict, said that "[t]he closest the prosecution had to a confession" were post-it notes found in Letby's handbag after her arrest. The notes bore hand-written jottings, one of which read, "I killed them on purpose because I'm not good enough to care for them." During the trial Letby denied this was a confession and that it was merely a reflection of her mental turmoil written while she was being investigated.^[120] The Telegraph also noted though that she had also suggested another motivation was her fear of never finding love or having children of her own, writing on the note: "I'll never marry or have children, I'll never know what it's like to have a family."^[98][97]

A former detective superintendent, the lead detective on the Beverley Allitt case of the 1990s, said that the amount of parallels between the cases made him think that "it's almost as if somebody's read the Allitt book" and that Letby's crimes may have been copycats.^{[75]: 17:30} Allitt had attacked over a dozen infants in her care while working as a nurse in Grantham, England, and the methods used in the cases were apparently identical, with Allitt having also injected some victims with air and insulin and physically assaulting them.^{[75]: 17:30} It was believed that Allitt may have been motivated by what was then called Münchausen syndrome by proxy, now known as factitious disorder imposed on another (FDIA), in which she harmed others to gain attention for herself and it may be that this also explains Letby's attacks.^{[75]: 18:00} Criminal psychologist Dominic Wilmott subscribes to this theory, commenting: "She wants to be involved in this case. She actually has the perfect opportunity not to be, right? So we expect most offenders to not want to get caught and to distance themselves from their offending behaviour. Beverley Allitt and Lucy Letby seemed to be injecting themselves into the inquiry, into the circumstances, so it shows that there's something else going on here."^{[75]: 18:10} Just like in Letby's case, the hospital in Allitt's case was criticised for its slow speed of response.^[122] Fellow criminal psychologist Dr David Holmes agrees that Letby was motivated by FDIA.^[95]31:15 Criminologist David Wilson agrees that in Letby's case, Letby seemed to have a "hero complex".^[122] A senior nurse testified on 21 March 2023 that Letby had told her before June 2016 that she, Letby, found non-intensive care of babies "boring" and had always wanted to be allocated to the intensive care unit, notwithstanding concerns among nursing staff that working long periods in intensive care would place a high burden on the mental health of nurses.^[11]

According to Wilson, healthcare killers like Letby "[have] already developed the desire to kill before they join the healthcare setting".^[122] Speaking on Newsnight, he said: "If you want to kill, of course you are going to identify people who are vulnerable. People whose deaths won't be noticed. And so guess what? The people that serial killers target, by and large, are older people, or they target very very young people, specifically in a neonatal unit in this case, where again small babies with chronic underlying healthcare where their deaths won't be commented upon or seen as being suspicious".^[122]

Post-conviction