Lucy Letby, a neonatal nurse who was convicted last year of murdering seven babies and attempting to kill six others at the English hospital where she worked, was found guilty on Tuesday of the attempted murder of another premature baby.

A jury had initially failed to reach a verdict in the case of the child, known as Baby K to protect her identity, and Ms. Letby was retried over the last four weeks in a court in Manchester in the north of England. She will be sentenced on Friday and is already serving life in prison for the earlier convictions. The yearslong case against Ms. Letby has haunted the country since suspicions around the deaths of a number of newborn babies first came to light in 2016.

The local police said they are still reviewing a period of time from 2012 to 2016 when Ms. Letby was working at the Countess of Chester Hospital in the city of Chester, in northwestern England.

Ms. Letby lost an attempt in an appeals court in May of this year to challenge her convictions, and a public inquiry into her crimes will begin in September. Earlier this year, The New Yorker magazine raised questions about the evidence the court relied upon.

Ms. Letby, 34, was working at the Chester hospital when, between June 2015 and June 2016, an unexpectedly high number of babies in the neonatal unit where she worked died or became seriously unwell.

During the recent four-week-long trial, the jury heard that Baby K was born in the early hours of Feb. 17, 2016, several weeks premature, before being transferred to the neonatal unit where Ms. Letby worked.