What a forensic-pathology investigation is
Forensic pathology is the sub-specialty that investigates deaths from a medico-legal perspective. A forensic post-mortem examination, on a suspected-crime death, is a different and more extensive procedure than a clinical post-mortem. It includes:
- Full-body post-mortem imaging (CT and/or MRI) before internal examination.
- Systematic histological sampling of every organ system.
- Toxicological screen for administered substances.
- Specific-mechanism investigation (e.g. for suspected air embolism: targeted cardiac imaging to identify intravascular gas; histology to distinguish artefact from genuine finding).
- Retention of physical exhibits (tubes, catheters, administered-medication containers, TPN bags).
- Chain-of-custody documentation for every sample and every exhibit.
- Independent blinded review by a second forensic pathologist.
This is the standard for any suspected-crime death worldwide. It is the standard UK coroners require for cases sent to Home Office pathologists.
What happened instead at the Countess of Chester
The Countess of Chester cluster was not initially investigated as suspected crime. It was processed as clinical neonatal mortality. Clinical post-mortems were performed where consent was given. The specific forensic procedures listed above were not systematically applied because the deaths were not, at the time, categorised as suspicious.
By the time Operation Hummingbird opened in May 2017, many of the forensic steps that would have been taken at the time of the deaths were no longer possible. The TPN bags had been discarded. Specific imaging had not been obtained. Specific histological sampling had not been done. Chain-of-custody documentation for the insulin samples was clinical not forensic. The physical investigation trail, to forensic standard, did not exist.
The specific gaps on the air-embolism counts
- No post-mortem imaging (CT or MRI) showing intravascular gas on any case.
- No specific cardiac histology demonstrating the locked-gas pattern the Lee 1989 paper describes.
- No retained tubes, catheters or syringes for forensic examination.
- No independent blinded forensic-pathology review commissioned at the time of the deaths.
The specific gaps on the insulin counts
- No confirmatory mass spectrometry on the Roche Cobas screening result.
- Samples processed at Royal Liverpool clinical laboratory under clinical, not forensic, chain of custody. The correct forensic laboratory (Guildford) was not used.
- No TPN bags retained. There are therefore no physical exhibits for the alleged mechanism.
- No syringes retained.
The specific gaps on the triplet counts (Babies O and P)
- Baby O’s liver findings were preserved and can be reviewed (and have been reviewed by independent paediatric pathologists since).
- Contemporaneous imaging showing or excluding deliberate impact was not obtained.
- A blinded forensic re-reading at the time would have included resuscitation injury as a primary differential; it did not.
Why the gaps matter
The Crown’s case on each indicted mechanism requires the mechanism to have occurred. Forensic investigation is how one distinguishes between “the mechanism occurred” and “the mechanism is inferred from clinical signs that have multiple causes”. Without the forensic investigation, the Crown’s theory is, at best, inference from non-specific signs — which is the problem the Shoo Lee Panel has formally identified.
The gaps are not now fixable. The physical material for most forensic tests no longer exists. What the CCRC can do is apply the forensic-evidence-absence to the conviction-safety question: a conviction on non-specific signs, without forensic-chain-of-custody exhibits, in the face of reputable expert disagreement, meets the Cannings principle.
What the Cheshire Police arrests of executives add
The July 2025 arrests of three former Countess of Chester executives on suspicion of gross negligence manslaughter indicate Cheshire Police themselves now regard the institutional handling as a matter of potential criminal liability. An institutional handling that has become a criminal matter at executive level cannot, by the same evidential standards, have produced a safe conviction at nursing level on the forensic gaps documented above.