Trial vs post-conviction
What changed since trial
A row-by-row comparison of what the jury heard at trial and what has emerged on the public record since, with each row labelled by claim type and source level. The Thirlwall Inquiry has not overturned anything; the CCRC has not decided anything. These are the dispute points feeding those processes.
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Showing 16 of 16 issues.
What the jury heard versus what has emerged on the public record since trial
| Issue | What the jury heard | What emerged later | Why it may matter | Status |
|---|---|---|---|---|
| Air-embolism evidence | Prosecution argued deaths and collapses were caused by deliberate intravenous air injection, citing the Lee & Tanswell 1989 paper for the skin-mottling diagnostic criterion. | Dr Shoo Lee, lead author of the 1989 paper, has publicly stated that his paper was misapplied at trial and that the skin-mottling descriptions on the record do not match his original criteria. The February 2025 International Expert Panel found no objective evidence of air embolism in the cases reviewed. | Air embolism was a central mechanism of harm for several murder counts. If the diagnostic basis is contested by the author of the paper relied upon, the safety of those convictions is open to expert challenge. | Post-conviction expert claim2Expert/professional |
| Insulin and C-peptide evidence | Prosecution presented immunoassay insulin-to-C-peptide ratios from the Royal Liverpool laboratory as forensic proof of exogenous insulin administration in two babies. | Named clinical biochemists (Prof. Adel Ismail, Prof. Geoff Chase and others) have argued that the immunoassays used were not validated for forensic interpretation, that confirmatory mass-spectrometry was not performed, and that interfering antibodies and the immunoassay hook effect were not excluded. | The insulin counts were treated as the strongest scientific evidence at trial. The dispute is over forensic validation methodology, not over whether the numbers were recorded. | Scientific literature2Expert/professional |
| Shift-chart / statistical reasoning | A chart was shown to the jury depicting Ms Letby's presence on the unit during a series of suspicious events, presented as visually striking evidence of association. | The Royal Statistical Society, Prof. Richard Gill, Prof. Norman Fenton, Prof. Jane Hutton, Prof. Peter Green and Prof. John O'Quigley (UCL) have all published critiques arguing the chart suffers from selection bias, base-rate neglect and Texas-sharpshooter logic. | Pure-statistical evidence of this type has previously been criticised in appellate cases (Sally Clark, Cannings). The CCRC will consider whether the chart's presentation to the jury fell within established standards for statistical evidence. | Statistical analysis2Expert/professional |
| Post-it notes | Handwritten notes found at Ms Letby's home (including 'I am evil I did this') were treated by the prosecution as confessional material. | Defence at trial and post-conviction commentators have argued the notes are consistent with self-blame psychology in a clinician under investigation, a documented response pattern in the patient-safety and resilience literature. | If the notes are open to a non-confessional reading, their weight as evidence depends on how a jury was directed to consider them, not on their face value. | Defence argument4Mainstream news |
| Facebook searches | Prosecution presented Facebook searches for parents of babies on the unit as evidence of preoccupation. | Independent commentators have shown the base rate of similar searches across the nursing population is non-zero, and that the searches identified at trial covered a small fraction of the post-shift period. | Behavioural evidence of this kind requires a comparator base rate to carry inferential weight. | Commentary5Commentary |
| Handover notes kept at home | Prosecution presented handover sheets found at Ms Letby's home as suspicious retention of confidential material. | Multiple consultant and senior-nurse witnesses at the Thirlwall Inquiry have stated that keeping handover sheets at home was common, sometimes routine, within the unit at the relevant period. | If retention of handover sheets was a unit-wide practice, the inference of consciousness of guilt becomes weaker. | Official inquiry evidence1Court/official |
| Door-swipe data | Door-swipe data was used at trial to place Ms Letby on the unit at relevant times. | Subsequent analysis has highlighted that swipe data is at the unit-entry level, not at the cot-side level, and that comparable swipe presence was recorded for other staff on shift at the same time. | Door-swipe presence does not by itself establish cot-side presence at the moment of a collapse. | Commentary5Commentary |
| Child K eyewitness evidence | Dr Ravi Jayaram gave evidence at the 2024 retrial that he saw Ms Letby standing over Child K without acting as the baby desaturated, leading to conviction on one count of attempted murder. | Independent clinicians have published technical analyses of the ET-tube and ventilation mechanism in Child K, arguing the timing and physiology of the collapse are consistent with displacement and re-intubation rather than deliberate harm. Defence has questioned the contemporaneous documentation of the alleged observation. | Child K is the only count where the prosecution relied on direct eyewitness observation of an act by Ms Letby. Its evidential safety is therefore central to that conviction. | Post-conviction expert claim2Expert/professional |
| Crown insulin expert's GMC investigation — undisclosed to jury | Prof. Peter Hindmarsh gave expert evidence for the Crown on the insulin counts (Babies F and L). His seniority was emphasised; no disclosure was made of any parallel professional investigation. | On the same day Hindmarsh began giving evidence the GMC opened a fitness-to-practise investigation; a Medical Practitioners Tribunal Service interim order concluded the allegations 'may have the potential to impact on his ability to act as an expert witness'. The Guardian (Lawrence and Conn) has reported that the CPS told the defence it would oppose any attempt to disclose the investigation to the jury, on the basis that the allegations had not reached a final adjudication. Hindmarsh voluntarily erased himself from the GMC register on 14 November 2024, ending the investigation without a regulatory finding. | Under Criminal Procedure Rules Part 19 an expert witness owes a primary duty to the court and must disclose matters affecting competence, credibility or independence. Non-disclosure is one of the central procedural grounds in the CCRC submissions on the insulin counts. | Post-conviction expert claim4Mainstream news |
| Door-swipe data mislabelling (CPS admission, August 2024) | Door-swipe records were presented as objective placement evidence used in connection with multiple counts. The jury was told the records placed Letby on the unit at material times. | The CPS confirmed in August 2024 that swipe data for one of the unit's doors was mislabelled — entries and exits had been reversed. Cheshire Police concluded the bad data was used in evidence relating to nine infants and was central to the Child K count. A second door recorded no entries or exits at all. | Contemporaneous documentary evidence the jury heard but which is later confirmed to be wrong is material to the unsafe-conviction standard the Court of Appeal applies on CCRC referral. Particularly significant for Child K, where the swipe data played a central evidential role. | Official inquiry evidence1Court/official |
| Expert methodology and disclosure | Lead prosecution paediatric expert Dr Dewi Evans was the principal medical reviewer of all counts; Dr Sandie Bohin served as a corroborating expert. | Subsequent expert critique has examined Dr Evans's chain of analysis on individual mechanisms, the route by which he became involved in the case, and the standard practice for paediatric expert evidence under the Criminal Procedure Rules. | Expert evidence is subject to duties under Crim PR Pt 19 and the Cannings principle. Where serious disagreement exists between reputable experts, courts have been cautioned against allowing convictions to rest on contested expert testimony alone. | Legal explanation2Expert/professional |
| Unit staffing, acuity and escalation | Unit conditions formed part of the defence at trial but were limited by available disclosure at the time. | The Thirlwall Inquiry record documents staffing shortfalls, acuity mismatch, sewage incidents, delayed transfers and governance failings during 2015–2016 in detail not available at trial. | Institutional context does not by itself displace individual criminal responsibility, but it bears on the prior probability of natural-cause explanations and on whether the unit was operating within its capability at the time of the deaths. | Official inquiry evidence1Court/official |
| RCPCH review | The 2016 Royal College of Paediatrics and Child Health invited review of the unit identified clinical-care concerns but did not identify a perpetrator. | Post-trial analysis has questioned the scope and limitations of the RCPCH review, and the way its findings were interpreted by the Trust and by investigators. | The RCPCH review was used at trial as a backdrop to the prosecution timeline. Its evidential weight depends on the questions it was asked to answer. | Commentary5Commentary |
| Police investigation framing | Operation Hummingbird was presented at trial as a long, careful investigation by Cheshire Police. | Subsequent analysis has examined the suspect-first scoping decisions, the relationship between Operation Hummingbird and Operation Duet, the role of the Beverley Allitt framing effect, and the December 2025 Hummingbird whistleblower report. | Investigative framing affects which evidence was sought and which alternatives were investigated. Most contested healthcare-serial-killer cases include this dimension on review. | Commentary5Commentary |
| Hospital governance failures | Trust governance was outside the trial's primary scope. | Thirlwall Inquiry evidence has documented the governance response in 2015–2016, the apology-letter sequence and the executive-level decision-making timeline. Three former senior executives were arrested in July 2025 on suspicion of gross negligence manslaughter (a separate investigation). | Governance failure does not by itself prove anything about the criminal counts, but it forms part of the institutional context the Inquiry is examining. | Official inquiry evidence1Court/official |
| Neonatal medical complexity | Each death and collapse was presented at trial through one or two named mechanisms of deliberate harm. | The February 2025 International Expert Panel and other named neonatologists have published natural-cause differentials for every count, including TTTS, late-onset sepsis, NEC, intrahepatic catheter complications, ventilation events and prematurity-related instability. | Neonatal collapse has a broad natural-cause differential. The CCRC will weigh whether the trial considered these differentials with the rigour now expected for medically-complex prosecutions. | Post-conviction expert claim2Expert/professional |
Each row links to the most detailed source-linked page on this site for that issue. None of these items is a court finding; together they form the body of material currently before the CCRC. The Inquiry is examining the institutional response separately.