When Dr. Shoo Lee, one of Canada’s most renowned neonatologists, wrote an academic paper in 1989, he never imagined it would one day help convict a British nurse of murder.

But more than three decades after his paper was published, that is what happened.

Lucy Letby, a former nurse in a neonatal unit in northern England, was found guilty in two trials in 2023 and 2024 of the murder or attempted murder of 14 babies in her care, and sentenced to life in prison, where she remains today.

The case rocked Britain, seeming to expose a remorseless serial killer who, prosecutors said, used a bizarre range of techniques to kill her tiny, often very premature, victims: Injecting them with air, overfeeding them with milk or contaminating their feeds with insulin.

For seven of the murder or attempted murder charges, the prosecution’s lead expert witness relied on Dr. Lee’s 1989 paper on a rare complication in newborns — pulmonary vascular air embolism — to argue that Ms. Letby had intentionally injected air into their veins.

The only problem? The expert witness had misinterpreted his work, Dr. Lee says.

“What they were claiming was that this baby collapsed and had skin discoloration, therefore that equals air embolism,” said Dr. Lee, 68, in an interview in London last month. But, he said, “That is not what the research shows.”