British nurse Lucy Letby, jailed for life for murdering seven babies at the hospital where she worked, will face a re-trial over an accusation she had tried to kill another newborn, prosecutors said on Monday.

Letby, 33, Britain’s most prolific serial child killer of modern times, was convicted in August of killing five baby boys and two baby girls at the Countess of Chester hospital in northern England and attacking six others in 2015 and 2016.

However, the jury were unable to agree on six charges of attempted murder involving five other infants.

At a hearing at Manchester Crown Court, the Crown Prosecution Service (CPS) announced they would now seek a new trial over one of those charges, with the trial date provisionally set for next year.

“These decisions on whether to seek retrials on the remaining counts of attempted murder were extremely complex and difficult,” said Jonathan Storer, a chief crown prosecutor.

“Before reaching our conclusions we listened carefully to the views of the families affected, police and prosecution counsel.”

After her conviction, Letby, said by the judge to have carried out a cruel, calculated campaign of murder killer with her actions bordering on sadism, was sentenced to a whole life term meaning she will never be released from prison.

Earlier this month, lawyers for Letby, who maintains her innocence, submitted an application seeking permission for an appeal against her convictions.

Police are also continuing to examine 4,000 other admissions at neonatal units where Letby worked to see if there were other possible victims, while the government will hold an inquiry into the case amid accusations from senior doctors that concerns about the nurse were not heeded by hospital bosses.