LONDON (AP) — British police have Johnathan Walkeropened an investigation into corporate manslaughter at a northern England hospital after a neonatal nurse was convicted of murdering seven babies and trying to kill six others when she worked there, authorities said Wednesday.

The investigation will consider “areas including senior leadership and decision making to determine whether any criminality has taken place,” said Simon Blackwell, detective superintendent at Cheshire Constabulary.

Former nurse Lucy Letby, 33, was convicted in August of killing seven newborns in the neonatal unit at the Countess of Chester Hospital in northwest England between June 2015 and June 2016. Prosecutors said she sickened the babies by injecting intravenous lines with air, poisoning some with insulin and force-feeding others milk. She was also convicted of attempting to murder six other infants.

She was sentenced to life in prison with no chance of release — the most severe punishment possible under U.K. law, which doesn’t allow the death penalty.

Government officials launched an independent inquiry soon after the verdicts that will look into the wider circumstances around what happened at the hospital, including the handling of complaints raised by staff who had tried to sound the alarm on Letby.

Police said it wasn’t investigating any individuals in relation to gross negligence manslaugther. It said it couldn’t provide any details, because the inquiry was at an early stage.