BBC raises syringe mix-up theory in Colin Norris murder case

A BBC investigation has raised the possibility that an accidental syringe mix-up during Ethel Hall’s hospital treatment could explain a blood test central to nurse Colin Norris’s conviction for her murder. [1]

Norris was convicted in 2008 of four murders and one attempted murder and received life imprisonment with a 30-year minimum term for the murders. The Court of Appeal upheld his convictions in June 2025. [2] [3]

The proposed syringe mix-up

BBC Disclosure Investigates reported on 25 September 2026 that two nurses were preparing separate 50ml syringes in the same treatment room. Norris was preparing dextrose — a glucose solution — for Hall, while another nurse was preparing insulin mixed with saline for a diabetic patient. The BBC raises the possibility that the syringes were accidentally exchanged. [1]

The timing is important. Hall had been found in a coma at about 05:00 on 20 November 2002 and received her first glucose injection at 06:15. The proposed exchange concerns syringes prepared afterwards, so it could not explain the initial collapse and hypoglycaemia, or low blood sugar. [1] [4]

The BBC quoted endocrinologist Professor Joel Zonszein as saying that the insulin Hall might have received accidentally would have produced the high readings in a blood test taken five hours later. He said the amount would not have caused severe illness and that a dextrose drip would have masked the insulin’s effects while leaving a very high reading in the test. [1]

The BBC also suggests that a strong opioid prescribed for postoperative pain might have caused Hall’s initial coma. Whether medication explains both her unconsciousness and her initial low blood sugar remains unresolved. [1]

Research into opioids and hypoglycaemia has found differences between drugs. A 2019 study of adverse-event reports found disproportionately frequent reports of low blood sugar with tramadol and methadone, but no significant increase for nine other opioids. Those associations do not establish causation or measure how often hypoglycaemia occurs among patients taking the drugs. [6]

The evidence and the appeals

The original case against Norris included evidence beyond the rarity of severe hypoglycaemia. The 2009 Court of Appeal judgment recorded very high insulin and undetectable C-peptide in Hall’s blood. It also described two insulin vials missing from the ward’s expected stock, with no recorded explanation for their use, and evidence that Norris had predicted Hall might deteriorate or die at about 05:15 that night. [4]

In February 2021, the Criminal Cases Review Commission referred the convictions for a fresh appeal after considering new expert evidence that the low blood sugar in the four patients other than Hall might have natural explanations. The commission considered that Hall’s conviction depended on support from those other cases and the prosecution’s assertion that nobody else could have been responsible. [3]

The June 2025 judgment reproduced a ruling that statistics about the rarity or frequency of unexplained hypoglycaemic deaths could not, by themselves, prove either responsibility or its absence. It also recorded that the jury could use a finding that Hall had received externally administered insulin when considering whether the other patients had been poisoned. [2]