Lucy Letby, a British neonatal nurse who is serving a life sentence for murdering seven babies and attempting to murder six others, was convicted Tuesday of trying to kill another infant in her care.

A jury found that Letby, 34, tried to kill a baby girl, known as Child K, in February 2016 at the Countess of Chester Hospital in northwestern England. A previous jury had failed to reach a verdict on the case. 

Letby, who testified that she never harmed a child, was accused of trying to murder the “very premature” child by dislodging her breathing tube in the early hours of Feb. 17, 2016. 

Senior Prosecutor Nicola Wyn Williams alleged that Letby removed the baby’s breathing support and a doctor found her standing by doing nothing as the child struggled. Williams said Letby removed the breathing tube two more times over the next few hours, “in an attempt to cover her tracks and suggest that the first dislodgment was accidental.”

“These were the actions of a cold-blooded, calculated killer,” she said. “Staff at the unit had to think the unthinkable — that one of their own was deliberately harming and killing babies in their care.”

Dr. Ravi Jayaram, a pediatrician at the hospital, told jurors he saw “no evidence” that Letby had done anything to help the baby as he walked in and saw her standing next to the newborn’s incubator.

Letby told the jury of six women and six men she had no recollection of any such event. She denied she harmed Child K, and testified that she had not committed any of the offenses she had been convicted of.

The parents of the baby gasped and cried as the verdict was read after three and a half hours of deliberations. Letby showed no emotion.

The Manchester Crown Court found Letby guilty of seven murders and six other attempted murders after over three weeks of deliberation in August 2023. All of the deaths took place at the Countess of Chester Hospital’s neonatal unit between June 2015 and June 2016. During the 2023 trial, Letby was accused of deliberately harming the newborn infants in various ways, including injecting air into their bloodstreams and administering air or milk into their stomachs via nasogastric tubes, as CBS News previously reported. 

Letby is already serving a life sentence with no chance of release — the most severe punishment possible under British law, which does not allow the death penalty. Only three other women have received such a harsh sentence in the U.K.