The clinical context
Baby B was born as a preterm twin at approximately 31 weeks, alongside her twin brother Baby A. Baby A died on 8 June 2015; Baby B collapsed the following night and was successfully resuscitated. The Crown’s pattern argument rested on a single act (on Baby A) followed by a further act (on Baby B) within 24 hours.
The prosecution theory
The Crown alleged an attempted-murder-by-air-embolism mechanism on Baby B, paralleling its theory on Baby A. The argument was that having “succeeded” in harming Baby A, Letby had attempted to harm Baby B via the same mechanism the following night.
What independent specialists read from the same record
- The post-sibling-death pattern is well recognised. A surviving twin, particularly in the early post-natal period after a sibling’s collapse, is at substantially elevated risk of sudden deterioration. The obstetric and neonatal literature treats this as a known pattern with natural-cause explanations. Baby B’s collapse pattern is not anomalous in a twin-pregnancy outcome framework.
- Shared placental and perinatal exposures. Twins share many perinatal risk factors — placental circulation, uterine environment, genetic background. If one twin decompensates for a natural cause, the other is at elevated short-term risk for the same reasons. Treating the two collapses as independent criminal events is not supported by the biology of twin pregnancies.
- Skin signs do not match Lee 1989. As with Baby A, the skin descriptions at Baby B’s deterioration do not meet the diagnostic specificity of the Lee & Tanswell 1989 paper’s criteria. Dr Shoo Lee himself has publicly said so.
- No post-mortem in a survivor. Baby B survived. Imaging or histology of the kind that would demonstrate intravascular gas in a deceased infant is obviously not available here. The inference of air-embolism is therefore entirely based on interpretation of clinical signs — the same signs the Panel and Dr Lee now say do not meet the 1989 paper’s threshold.
- Successful resuscitation is evidence of non-lethal mechanism. If a full-dose deliberate air-embolism act had occurred, recovery with standard resuscitation would be unusual. Baby B’s recovery is consistent with a less catastrophic natural deterioration than the Crown’s theory proposed.
Why this case is anchor-dependent
The conviction on Baby B was argued to the jury in the context of the Baby A conviction: the pattern was one death followed by one attempt. If Baby A’s death was natural — the independent reading we explore in our Baby A deep-dive — then Baby B’s collapse is not a pattern event. It is the second deterioration in a surviving twin, which obstetric literature treats as naturally elevated-risk.
The Panel reading on Baby B
The Shoo Lee International Expert Panel reviewed Baby B as part of its case-by-case methodology. Baby B was the surviving twin of Baby A; the deterioration she experienced occurred within 24 hours of her co-twin’s death. The Panel’s reading identifies the deterioration as consistent with a well-documented preterm-twin clinical pattern: surviving-twin instability following co-twin death, mediated by sympathetic catecholamine surge, stress-related cardiovascular and respiratory instability, and feeding intolerance.
No physical evidence of air embolism was identified in Baby B’s clinical record (no intravascular gas, no embolism-associated organ findings). The non-specific skin mottling documented at the time of the deterioration is the same clinical sign documented in the other air-embolism counts and is the sign Dr Shoo Lee himself has publicly stated his 1989 paper does not support as diagnostic of venous air embolism.
The pattern-dependence problem
Baby B’s conviction was argued to the jury within the wider air-embolism pattern across Babies A, C, D, E, I, O, P. If the air-embolism pattern is not sustained on the underlying cases — and the Panel finding is that it is not — the attempted-murder conviction on Baby B rests on a foundation of other convictions that independent review does not support. This is the structural logic of the CCRC review.
What the jury did not hear on Baby B
- Dr Shoo Lee’s February 2025 statement that his 1989 paper’s skin-sign criteria do not match the descriptions at trial.
- The documented preterm-twin literature on surviving-twin instability following co-twin death.
- The Panel’s case-by-case finding on Baby B.
- The structural sympathetic-catecholamine-surge mechanism by which bereaved-preterm-twin instability arises.
- The pattern-dependence of the Baby B conviction on the air-embolism cases the Panel finds unsustained.