Colin Norris: Biography and Background

Colin Campbell Norris (born 12 February 1976) is a British serial killer who was convicted of the murder of four elderly patients and the attempted murders of two others in two hospitals in Leeds, England, in 2002.

A police investigation showed Norris to be on duty when five patients fell into sudden hypoglycaemic comas. Suspicions were raised when Norris predicted that healthy Ethel Hall would die at 5:15 am one morning, which is when she went into cardiac arrest, and tests revealed that she had been injected with an extremely high level of man-made insulin. Insulin was missing from the hospital fridge and Norris had last accessed it, only half an hour before Hall fell unconscious.

Subsequent investigations would find that the unnatural hypoglycaemic attacks followed him when he was transferred to a second hospital, and hospital records revealed that only he could not be eliminated as a suspect. Detectives believed that Norris was responsible for up to six other suspicious deaths where only he was always present, but a lack of post mortem evidence and other factors meant that investigators and the Crown Prosecution Service could not pursue convictions for these deaths.

Doubts were later raised about his conviction by, among others, Vincent Marks, an expert on insulin poisoning, who concluded from his own studies that there was a 1 in 10 chance that each patient's arrest could have happened naturally. However, others have pointed out that C-peptides are produced in hypoglycaemic attacks caused by insulin produced naturally in the body, and these were not detected in any of the blood tests of the victims, indicating that the insulin had been introduced to their bodies externally and artificially. Norris lost an appeal against his conviction in 2009. In February 2021, the Criminal Cases Review Commission referred the case back to the Court of Appeal; this second appeal, heard in 2025, was also unsuccessful.

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