The clinical context
Baby M was a preterm twin on the Countess of Chester neonatal unit during the indictment period. He survived his deterioration event and went on to recover. His twin was also on the unit at the material time. The family context is that of a twin pregnancy with significant preterm-twin-pair neonatal-intensive-care requirements — which itself is a documented high-risk category for unexpected deterioration events in the published UK neonatal literature.
The clinical record documents a specific deterioration event in which Baby M required resuscitation. The non-specific skin mottling documented in the notes at the time is the same clinical sign documented in the other air-embolism counts and is the sign Dr Dewi Evans identified as supporting his air-embolism theory.
The prosecution theory
The Crown’s case on Baby M was that Ms Letby injected air into the baby’s venous line, producing a sudden cardiovascular deterioration through intravascularair embolism, from which the baby was successfully resuscitated. Dr Evans identified the deterioration as consistent with his air-embolism framework. The theory mapped the clinical picture onto the Lee & Tanswell 1989 paper’s description of skin signs in venous air embolism. The jury returned a conviction for attempted murder.
Central to the Crown’s case was the pattern argument: if Babies A, C, D, E, I, O, and P were all air-embolism cases with similar clinical signs, then Baby M fits the pattern. The pattern-based inference was load-bearing. See the ‘gang of four’ framing evidence and the circular evidence entry.
What independent specialists read from the same record
- Skin signs do not match Lee 1989. As with the other air-embolism counts, the skin descriptions at Baby M’s deterioration do not meet the diagnostic specificity of the Lee & Tanswell 1989 paper’s criteria. See our air-embolism line-by-line analysis.
- Twin-pregnancy baseline instability. A preterm twin with a central venous catheter is at elevated risk of sudden deterioration from natural causes including thrombosis, circulatory collapse, and respiratory instability. See our twins and multiples deep-dive.
- Successful resuscitation is evidence of a non-catastrophic mechanism. A full-dose deliberate air embolism would normally be expected to produce an unrecoverable event. Baby M’s successful recovery is consistent with a less catastrophic natural deterioration than the Crown’s theory required.
- No post-mortem confirmation available. Baby M survived, so no pathological confirmation of air embolism is available. The theory rests on clinical signs — the same signs Dr Shoo Lee himself says do not meet his 1989 paper’s criteria.
The pattern dependence
The conviction on Baby M was argued to the jury in the context of the wider air-embolism pattern: Baby A, Baby C, Baby D, Baby E, Baby I, Baby O, Baby P. If the air-embolism pattern is not sustained on the underlying cases — and the Panel’s finding is that it is not — the attempted-murder conviction on Baby M rests on a foundation of other convictions that independent review does not support. This is the structural logic of the CCRC review: Baby M is not a case that stands independently; it is a case that depends on the pattern inference, and the pattern inference depends on the air-embolism cases, and the air-embolism cases depend on Dr Lee’s 1989 paper being correctly applied — which Dr Lee himself has now publicly stated was not the case.
The Panel’s specific finding on Baby M
The Shoo Lee International Expert Panel reviewed Baby M as part of its case-by-case review. The Panel’s reading identifies the deterioration as consistent with natural-cause differentials documented in the literature for preterm twins with central venous catheters: thrombosis (the elevated risk in preterm twins with indwelling lines is well documented), cardiorespiratory instability (common in the early days of preterm twin intensive care), circulatory collapse from infection (sepsis remains unexcluded in the clinical record), and transient hypoxic-ischaemic event. No objective evidence of air embolism is identified on the clinical record. The full Panel report and the June 2025 Additional 10 Cases report both address Baby M.
What the jury did not hear
- Dr Shoo Lee’s February 2025 statement that his 1989 paper’s skin-sign criteria do not match the descriptions at trial.
- The Panel’s case-by-case finding on Baby M.
- The elevated baseline risk of spontaneous deterioration in preterm twins with central venous catheters.
- The Lucia de Berk parallel and the Sally Clark parallel on pattern-inference architecture (both established through successful CCRC referrals that the Letby jury did not see).
- The base-rate context for cardiovascular collapse in preterm NICU infants; see the base-rate analysis.