Medical and scientific open questions
- What caused each individual death. The Panel’s finding is that no case meets the diagnostic criteria for deliberate harm; this is not the same as a positive case-by-case reassignment of cause of death. In several cases the primary cause of death at the time of death remains unresolved between specific differentials (IVH, sepsis, NEC, cardiovascular instability, viral outbreak) because the SUDI/SUDIC-standard evidence that would have distinguished them was not collected at the time. See SUDI/SUDIC protocols.
- Whether viral outbreak played a role in the cluster. No retrospective viral testing of stored samples has been undertaken, and in many cases the samples are no longer available. Enterovirus / parechovirus remain unexcluded but also unconfirmed. See viral-outbreak differential.
- What the TPN bags actually contained. The Crown’s insulin theory required Ms Letby to have spiked TPN stock, but the bags were not retained for forensic analysis. We will never know what those specific bags contained. See TPN bag chain-of-custody.
- Whether any Royal Liverpool sample would show a different reading on mass-spectrometry today. Most of the original samples are no longer available in storage; the question cannot now be retrospectively tested against the Guildford forensic standard.
Legal and procedural open questions
- Whether the CCRC will refer the case to the Court of Appeal. The application was filed October 2025; the CCRC publicly confirmed the review is underway February 2026. Median application-to-decision time for complex cases is 12–24 months. No timetable has been published. See CCRC review explained.
- Whether the Thirlwall Inquiry will publish findings that affect conviction safety. Thirlwall’s terms of reference are scoped to institutional failings, not conviction safety. Its document-discovery process has surfaced material that bears on both, but the Inquiry itself is not a retrial and is not empowered to revisit the verdict. See why Thirlwall matters.
- Whether the three former Trust executives will be charged. All three were arrested on suspicion of gross negligence manslaughter in July 2025; charging decisions are ongoing. See timeline: executives arrested.
- What disclosure under CPIA 1996 actually included and didn’t include. Categories of material the defence argues should have been disclosed but were not are part of the CCRC submission; the full disclosure record has not been published. See CPIA disclosure.
Institutional and investigative open questions
- The full internal decision chain at the Countess of Chester in 2015–2016. The joint consultants’ letter of September 2016 is on the record; the internal Trust Board papers leading to the eight-month delay before police referral are partially disclosed through Thirlwall but not yet fully public.
- What the Cheshire Police Operation Hummingbird investigation considered and rejected. The Hummingbird whistleblower report (December 2025) alleges a suspect-first investigative frame. Cheshire Police has not published its full case papers; what alternatives were considered and rejected remains unknown.
- The full expert-instruction decision trail for Dr Dewi Evans. Dr Evans self-referred to Cheshire Police offering his services in 2017. The full correspondence trail between Evans and the investigation is not in the public record. See suspect-first scoping.
Questions that may never be resolved
- The cause of death of individual infants. SUDI/SUDIC-standard evidence was not collected at the time; retrospective certainty is not recoverable.
- Counterfactuals: what would have happened if the RCPCH review had been a forensic investigation. Different evidence would have been preserved. The investigative path would have been different.
- Private elements of Ms Letby’s psychological state at specific moments during the indictment period. The handwritten notes and Facebook-search data are available but their subjective significance is a matter of interpretation; the CCRC review engages this interpretively rather than definitively.
Why we list these
An evidential case that depends on pretending there are no open questions is a weak evidential case. The post-conviction review is strong enough that the open questions above are reasons to take it seriously, not reasons to dismiss it. A criminal conviction that cannot withstand acknowledgement of its open questions is a conviction under which the open questions have been suppressed, not resolved.
If you disagree with anything on this page, tell us via /contact. Where new information closes one of the questions above, we will update this page and log the change in the changelog.