The Lucy Letby Case

In the mid-2010s, Countess of Chester Hospital in northwest England experienced an unusual spike in both baby deaths and unexplained infant collapses in its neonatal unit, raising early alarms among staff and management.

This period of increased fatalities occurred during ongoing national scrutiny of patient safety and whistleblower protection within the U.K.'s National Health Service (NHS), in the wake of other health care scandals. Studies in recent years have found that health improvements in the U.K., including neonatal care, have largely stalled since 2010.

Austerity Measures

Following the 2008 financial crisis, the U.K. implemented austerity measures, leading to below-inflation increases in NHS funding. This resulted in stretched budgets, reduced staffing, delayed infrastructure upgrades and longer waiting times for treatments, contributing to public dissatisfaction despite efforts to maintain care quality.

Still, the NHS maintained strong clinical outcomes, such as cancer survival rates, compared to other developed nations' health systems. The Commonwealth Fund's 2017 rankings praised the NHS for efficiency and equity, often outperforming systems like those in the United States, though it lagged behind some European peers in timely care delivery.

Early Concerns and Investigations

As early as 2015, Countess of Chester Hospital consultants noticed a clear rise in unexpected neonatal deaths, prompting internal discussions and the involvement of external bodies such as the Royal College of Paediatrics and Child Health. Despite these investigations, no definitive cause was found at the time, with internal culture and communication issues emerging as significant concerns.

Staff and Systems Issues

The hospital's leadership and management were criticized for their handling of early warnings, with documented allegations that concerns raised by clinical staff about patient safety were not addressed promptly or transparently. The subsequent appointment of public inquiries and a focus on systemic factors reflected growing national awareness of institutional deficiencies and patient protection.

Between 2015 and 2016, a cluster of unexplained collapses and fatalities occurred in the Countess of Chester's neonatal unit.

Notably, internal records show that these incidents happened across multiple shifts and were observed by different staff members, with nurse Lucy Letby reportedly present for all of the most concerning incidents. However, there were other infant deaths when Letby was not on duty, though these were largely not considered "unusual."

Patterns and Early Responses

Some deaths and collapses, including those involving twins and triplets, led to heightened internal scrutiny. Despite an early correlation noted between Letby's presence and the events, formal decisions to remove her from the ward or contact police were not made until months after initial concerns were raised. Some staff later testified about delays in addressing potential issues, citing challenges in identifying clear causes at the time.

Diversity of Incident Types

The incidents ranged from sudden, catastrophic collapses to unexplained hypoglycemia. Several babies died within a short period, while others suffered life-threatening events but survived. These diverse clinical events complicated efforts to interpret the true underlying causes, as later explored by both prosecution experts and independent reviews.

Transition to Formal Charges

The patterns of infant deaths and collapses, combined with the correlation to Letby's presence, eventually prompted hospital leadership to escalate concerns to law enforcement in May 2017, following internal and external reviews that failed to pinpoint a definitive cause. This marked a critical shift from internal hospital scrutiny to a formal criminal investigation.

Following a lengthy investigation into the deaths and collapses on the neonatal unit, Lucy Letby was charged in November 2020 with eight counts of murder and ten counts of attempted murder involving babies in her care between 2015 and 2016.

Letby was accused of causing intentional harm to infants through a variety of means, including injecting air into bloodstreams or stomachs, giving insulin overdoses and tampering with medical equipment such as breathing tubes. The circumstances were said to be covert and left little forensic evidence, complicating definitive attribution.

Modifications and Scope

After revising the charges, Letby was ultimately put on trial for murdering seven infants and the attempted murder of seven more. The authorities initially considered charging Letby with additional counts related to the deaths or collapses of other infants at the Countess of Chester Hospital, but these were dropped before the trials due to insufficient evidence.

The Crown Prosecution Service explicitly stated that all evidence was carefully considered in bringing such serious criminal charges, and Letby continued to deny all accusations. The charges sparked widespread scrutiny of both the unit and the legal processes involved.

Clinical Presentations and Investigations

Reported incidents included sudden collapses in infants who were previously stable and the occurrence of high insulin levels in babies. Other allegations involved overfeeding with milk and physical assaults. Prosecutors relied on detailed clinical records, including blood test results and X-rays, in building their arguments.

Challenges in Attribution

The lack of direct eyewitness evidence or forensic proof led to a reliance on circumstantial, statistical and expert medical interpretation. Several later reviews and expert panels highlighted the complexity of distinguishing between deliberate harm and rare but plausible medical complications in critically ill neonates.

Lucy Letby was first arrested at her Chester home in July 2018, after a protracted police investigation began in 2017 in response to concerns raised by staff regarding the spike in newborn deaths and collapses.

She was questioned at length and her house was subject to intensive forensic searches, with the police digging up her back garden and examining drains and vents. The investigation into Letby was codenamed Operation Hummingbird by Cheshire Constabulary and was initially prompted by a review from retired pediatrician Dr. Dewi Evans, who analyzed 61 cases and identified suspicious patterns.

The probe focused on eight deaths and seven further incidents, later expanding to include around 30 "suspicious" cases at the hospital and additional inquiries into Letby's placements at Liverpool Women's Hospital in 2012 and 2015, where no charges resulted.

Led by Detective Superintendent Paul Hughes as the senior investigating officer, the six-year operation involved over 200 staff members, extensive forensic analysis (including insulin testing and air embolism evidence), multiple property searches that uncovered allegedly incriminating items like handover notes and medical records at Letby's home and collaboration with medical experts to build a case without direct witnesses to the acts.

Detentions and Procedure

Letby was arrested multiple times: in 2018, 2019 and finally in 2020, each time as part of the ongoing investigation as police reviewed additional cases and evidence. Following her third arrest in November 2020, formal charges were brought, and she was remanded in custody to await trial.

Legal Process and Controversy

Her arrests drew national and international media attention, due to both the severity of the allegations and the rarity of such charges against health care practitioners in Britain. Police emphasized the complexity and sensitivity of the case, citing the need for thorough review and support for the affected families.

The Telegraph released a report in early 2025 alleging that Cheshire Police paid a media advisory company run by Caroline Cheetham, co-host of the Daily Mail podcast about Letby, nearly £24,000 since 2022 for "publicity" and "external training courses." The revelations prompted concerns regarding conflict of interest and raised the possibility that police had worked to influence how the media covered the case.

Letby's first criminal trial commenced in October 2022 at Manchester Crown Court and continued for nearly ten months, making it one of the longest in recent British history.

The case spanned multiple hearings, jury deliberations and the presentation of thousands of pages of clinical and expert evidence. The first trial at Manchester Crown Court resulted in convictions for seven murders and six attempted murders, but the hung jury on the remaining counts prompted a second trial (June-July 2024) specifically for the attempted murder of "Baby K," for which Letby was convicted and received an additional whole-life sentence.

Key Evidence and Testimony

The prosecution presented a wide array of circumstantial evidence, including clinical data, staffing rosters, patterns of presence at incidents and handwritten notes discovered at Letby's home. The defense challenged both the interpretation of such evidence and the reliability of prosecution experts, while also highlighting alternative explanations for the medical events.

Jury Deliberations

The jury deliberated for more than 100 hours over nearly four weeks, ultimately returning guilty verdicts on most charges, but remaining undecided on some. The trial was marked by tight press reporting restrictions, with some information released only after the final verdicts.

The prosecution presented a case focused on Letby's alleged pattern of harming infants in ways consistent with a deliberate, covert perpetrator.

They contended that clinical records and staff rosters consistently showed Letby present during each critical event, with circumstantial medical evidence supporting the theory of non-accidental harm over rare but natural causes.

Expert and Witness Testimony

Key medical experts for the prosecution argued that events such as sudden hypoglycemia, air embolism and insulin overdose in otherwise stable infants could only have resulted from intentional intervention. The sequence and similarity of these incidents, according to the prosecution, supported the inference of guilt, rather than coincidence or system failure.

Dr. Dewi Evans, a retired consultant paediatrician, served as the lead prosecution expert witness in Lucy Letby's trial, testifying that he suspected foul play almost immediately upon reviewing the medical records of the affected babies, attributing their collapses and deaths to deliberate acts such as air injection via nasogastric tubes.

The testimony he provided was pivotal in linking Letby to the incidents through analysis of duty rosters showing her presence during each event, and he opined specifically on cases like "Baby C," where he initially described air in the stomach causing fatal organ compression, though he later clarified his view on the exact mechanism while maintaining her guilt. Despite defense challenges to his reliability, the Court of Appeal upheld the admissibility of his testimony, supporting the jury's convictions.

Dr. Ravi Jayaram, a consultant paediatrician at the Countess of Chester Hospital, alleged during Letby's trials that he walked into a nursery in February 2016 and found her standing over the incubator of a premature infant known as "Baby K," without taking any action as the baby's breathing tube had been dislodged, leading to a rapid deterioration in her condition.

He testified that Letby had not called for help despite the emergency, which he believed indicated deliberate harm, and this incident became a key piece of evidence in her conviction for the attempted murder of Baby K. Jayaram expressed regret at the Thirlwall Inquiry — set up following Letby's trial and convictions — for not reporting his suspicions earlier due to fear and lack of concrete proof, though recent leaked emails have raised questions about whether Letby had actually summoned assistance, potentially contradicting his courtroom account.

Use of Circumstantial Evidence

During a police search of Lucy Letby's home in 2018, investigators found handwritten notes, including one with phrases like "I am evil I did this" and "I killed them on purpose," which prosecutors presented as a confession during her trials for the murder and attempted murder of infants at the Countess of Chester Hospital. Police also found notes in Letby's home saying "I haven't done anything wrong" and variations like "I'm innocent."

Letby claimed these notes were not admissions of guilt but reflections of her distress and self-blame, written under mental health strain, as she testified at the Thirlwall Inquiry. The notes, alongside other evidence, played a significant role in her conviction, though some recent analyses question their interpretation, citing potential confirmation bias in the prosecution's case.

At the time, Letby was receiving mental health support, including counseling sessions and occupational health therapy. Sources close to the case indicate that the notes, including those with phrases like "I am evil I did this," were produced as part of a therapeutic process advised by her GP and Kathryn de Beger, the head of occupational health and wellbeing at the Countess of Chester Hospital, to help her cope with extreme stress following her suspension from duties in 2016.

The prosecution also further relied on historical parallels and statistical analyses, while anticipating and addressing potential alternative explanations offered by the defense.

Letby's defense centered on the lack of direct forensic evidence and the possibility that clinical incidents could be attributed to medical error, natural complications or hospital system failures.

Her legal team argued that the prosecution's reliance on circumstantial evidence and the use of statistical inference was problematic and potentially misleading. The defense added that systemic problems at the Countess of Chester Hospital's neonatal unit, such as understaffing, inadequate training and poor hygiene practices, contributed to the infants' deaths and collapses, rather than deliberate acts by Letby.

Critique of Expert Evidence

The defense challenged the prosecution's expert witnesses, contending that some had no direct experience with specific neonatal complications or had formed conclusions based on patterns rather than individual case analysis. The team also cited alternative expert reviews that found the events could have been explained without recourse to deliberate harm.

Notably, no expert witnesses for the defense testified in court. Court records and the judge's summing-up confirm that the defense instructed several medical experts, who provided reports, participated in pre-trial expert conferences — joint discussions with prosecution experts without lawyers present — and were involved in preparing the case. However, Letby's defense counsel chose not to call any to the stand. This decision has been widely discussed and criticized post-trial, with some experts later expressing regret or concern that their input could have challenged the prosecution's narrative more directly

Emphasis on Institutional Issues

The defense called attention to systemic problems within the hospital, such as staff shortages, equipment failures and the presence of rare but recognized medical conditions. Letby herself denied all allegations, testifying that she never harmed any child and was a scapegoat for broader institutional shortcomings.

Notably, documents revealed after her conviction showed Letby had raised concerns with hospital management about understaffing and inadequate resources prior to the incidents, warning that these issues could compromise patient safety. Her alerts, documented in internal communications, were largely dismissed or inadequately addressed.

The defense also highlighted issues like plumbing problems potentially linked to infections and the unit's unpreparedness for handling extremely premature babies, suggesting these factors created conditions where natural or accidental causes were plausible. Through cross-examination of prosecution witnesses, the defense sought to show that hospital mismanagement and environmental issues were overlooked in favor of attributing blame to Letby.

Letby was ultimately found guilty of seven counts of murder and seven of attempted murder across the two trials, with one infant said to have been attacked on multiple occasions.

She was acquitted of some charges, and for several counts, the jury could not reach a verdict.

Sentencing and Legal Outcome

Letby was sentenced to 15 life terms, each a whole-life order, meaning she would never be eligible for parole. The judgement emphasized the severity of the offenses and the trust breach involved, with the presiding judge stating the crimes warranted the highest penalty available in British law.

Subsequent Developments

A public inquiry and further police reviews of hospital leadership and other cases were launched in the verdict's wake. The legal process and outcome divided opinion among clinicians, legal experts, the media and affected families, with ongoing debate over the robustness of both the evidence and the jury's conclusions.

Letby's legal team launched immediate appeals following her conviction, concentrating on the admissibility and interpretation of expert and statistical evidence presented at trial.

Multiple grounds for appeal were submitted, including challenges to the trial judge's decisions.

Court of Appeal Review

Lucy Letby's initial appeals against her convictions from the first trial were submitted shortly after her August 2023 sentencing, with her original legal team arguing that the trial judge erred in refusing certain applications during the proceedings, including those related to jury directions, evidence admissibility and procedural fairness. These appeals were heard by the Court of Appeal in London in April 2024, but permission to appeal was denied in May 2024, with the judges ruling that the arguments lacked merit and that the trial was conducted fairly.

Further Applications and Review Bodies

In response to these failures, Letby replaced her legal team in early 2025, appointing Mark McDonald KC as her new barrister, who submitted an application to the Criminal Cases Review Commission (CCRC) in February 2025, based on fresh expert evidence from an international panel of neonatologists challenging the prosecution's medical interpretations (e.g., air embolisms and insulin poisoning) and highlighting systemic hospital issues.

The CCRC is conducting an ongoing review, which could take years due to the case's complexity, potentially leading to a referral back to the Court of Appeal if new arguments show a "real possibility" of overturning the convictions.

An international panel of neonatologists and statisticians that convened in February 2025 brought heightened attention to the safety of Letby's conviction, disputing the prosecution's interpretation of clinical evidence and suggesting that many incidents could have resulted from natural causes or suboptimal care.

The panel, assembled pro bono by Letby's defense team, reviewed the full medical records, autopsy reports, and trial evidence for the 14 babies involved in the convictions (out of 17 originally charged). They concluded that all deaths and collapses were attributable to natural causes, such as prematurity-related complications or infections, or substandard medical care at the under-resourced unit, rather than deliberate harm like air injections or insulin poisoning. The experts emphasized systemic issues, including poor staffing, delayed treatments, and inadequate infection control, as key factors.

This report was presented at a press conference in Westminster, London, organized by Letby's barrister, Mark McDonald, alongside Conservative MP Sir David Davis, who called it "one of the major injustices of modern times." The findings were submitted to the Criminal Cases Review Commission (CCRC) as potential new evidence for an appeal, arguing they were not available or fully explored during the original trial.

As of September 2025, the CCRC is reviewing the case but has not yet referred it to the Court of Appeal. The Crown Prosecution Service (CPS) maintains the convictions are safe, citing two juries and multiple judges who upheld them after reviewing extensive evidence.

Ongoing Disagreements

Some of the prosecution's own expert witnesses have since modified their opinions concerning specific deaths, while other senior clinicians and epidemiologists questioned whether systemic errors and rare events best explained the observed patterns rather than malice. Defense experts also questioned the objectivity and experience of prosecution experts, noting lessons from previous miscarriages of justice involving health care workers.

The February 2025 expert panel disputed the testimony of Dr. Dewi Evans, particularly his air embolism theory. The panel claimed that the theory relied on misinterpretations and did not fully account for natural causes or systematic failures at Letby's unit.

An email written by Dr. Ravi Jayaram, a key witness in Letby's two trials, in May 2017 suggests Letby did summon Jayaram proactively when Baby K's condition worsened, directly contradicting his later claims that she stood by passively without alerting anyone. The email also reportedly included Jayaram's initial view that Baby K's issues were due to extreme prematurity complications, not deliberate harm — another point not emphasized in court.

However, Cheshire Police's Detective Superintendent Paul Hughes, dismissed the email as "ill-informed" and insisted the full evidence, including non-medical elements like shift patterns, remained robust. The police maintain the email was disclosed appropriately for appeals. Jayaram has not publicly commented on the email since its release, though his testimony to the Thirlwall Inquiry in November 2024 indicated that he felt regret for not reporting suspicions sooner, saying it "keeps me up at night," but stood by his trial account.

Broader Implications

The ongoing controversy led to increased calls for reform in the handling of expert evidence in court and inferences drawn from statistical anomalies. The case has provided a focal point for broader debates on the reliability and governance of expert witness testimony in complex criminal cases.

Following Letby's conviction, public inquiry and police investigations widened to probe the possible roles of hospital management and NHS systems in both the persistence and detection of patient harm.

Three former senior leaders at the trust were arrested on suspicion of gross negligence manslaughter in June 2025. These unnamed individuals were part of the hospital's senior leadership team during the period when concerns about increased fatalities in the neonatal unit were raised but allegedly not adequately addressed, leading to scrutiny of their decision-making and potential inaction.

The arrests stem from a corporate manslaughter probe launched in October 2023, which was expanded in March 2025 to include gross negligence manslaughter — a charge focusing on individual failures rather than organizational ones. All three suspects were released on bail, and the investigation continues without impacting Letby's convictions.

No formal charges have been filed yet, but the probe examines whether leadership failures, such as ignoring doctor warnings or systemic issues like understaffing, contributed to the deaths and injuries at the hospital. A separate public inquiry, known as the Thirlwall Inquiry, is also reviewing hospital responses, with its final report expected in early 2026.

Media and Public Debate

The case has been subject to unprecedented attention, with parallel discussions emerging in mainstream and independent media regarding statistical evidence, the complexity of medical judgment and the risk of miscarriages of justice in health care settings. Families of victims and hospital officials alike have responded to the inquiries, criticisms and ongoing media coverage.

Key recent events include a February 2025 expert panel's conclusion of "no evidence" for deliberate harm, pointing to natural causes and poor care at the Countess of Chester Hospital; parliamentary debates led by MP Sir David Davis in January 2025, where he highlighted suboptimal care by accusers and called for a retrial; and online discussions, such as on Reddit and X, where medical professionals and the public are divided, with some viewing it as a modern echo of past wrongful convictions like that of Lucia de Berk.

This controversy has broader implications for trust in the NHS and justice system, fueling calls to expand the Thirlwall Inquiry's scope and ongoing reviews by the Criminal Cases Review Commission.

Broader Lessons and Reforms

The Letby case has sparked debates on whistleblower protection, expert witness regulation, and NHS culture. Calls for new laws, reforms in criminal appeals, and improved hospital oversight continue, with the Thirlwall Inquiry expected to make system-level recommendations to reduce the risk of future patient harm and to strengthen both clinical and legal safeguards.