Child L
The prosecution’s theory: Insulin in feeds.
Outcome: Survived
Gestation: Twin 1; 33+2 weeks, 1.465 kg, severe intrauterine growth restriction
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Prosecution theory
Insulin in feeds.
Method alleged: Exogenous insulin administered in enteral feeds.
Prosecution experts: Prof. Peter Hindmarsh (UCL / Great Ormond Street); Royal Liverpool biochemists.
Panel view (Feb 2025)
Panel: hypoglycaemia was due to preterm birth and severe IUGR, and its medical management was inadequate. The insulin and C-peptide results do not prove exogenous insulin and are within the norm for preterm infants.
Pathology
No fatal outcome. Panel conclusion: the hypoglycaemia was due to preterm birth and severe intrauterine growth restriction, and its medical management was inadequate; the insulin level and insulin/C-peptide ratio do not prove that exogenous insulin was used and are within the norm for preterm infants, who have different normative standards from healthy adults and older children. The Chase and Shannon bioengineering analysis annexed to the Panel report (covering Babies 6 and 12 — Children F and L) reaches the same conclusion by a separate route: C-peptide and potassium were not suppressed, the observed glucose was far higher than genuine exogenous insulin at the alleged levels would produce, and the immunoassay used is not of forensic quality.
Natural-cause alternatives identified
- Preterm birth with severe IUGR causing hypoglycaemia — the Panel's stated cause
- Inadequate medical management of the hypoglycaemia
- Insulin autoantibodies and immunoassay interference inflating the measured insulin level
- Preterm-specific insulin/C-peptide normative ranges (adult reference ranges do not apply)
What the jury did not hear
- The Panel's conclusion that the hypoglycaemia was caused by prematurity and severe IUGR, with inadequate management.
- That the insulin/C-peptide ratio was within the normal range for preterm infants.
- The Chase and Shannon analysis: the immunoassay is not of forensic quality and unexpected results should have been confirmed by gold-standard methods.
Key primary sources
- International Expert Panel — Additional 10 Cases report (June 2025), Panel Baby 12: https://lucyletbyinnocence.com/shoo-lee/International%20Expert%20Panel%20New%20Summary%20Report%20of%20additional%2010%20cases.pdf
- R v Letby sentencing remarks (August 2023)
- Joint Expert Witness Insulin Report on Babies F and L (May 2025)
- science4justice.nl — 'The insulin question'
Read the full long-form analysis →
Sources:
- Court of Appeal judgment (May 2024) and sentencing remarks — judiciary.uk
- Shoo Lee International Expert Panel Report (February 2025) — lucyletbyinnocence.com
- Per-baby trial evidence archive — lucyletbyinnocence.com
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