Lucy Letby trial told poisoner was at work at baby deaths hospital

A "poisoner was at work" at a hospital where there was a "significant rise" in the number of healthy babies dying, a court has heard.

Lucy Letby has been accused of murdering five baby boys and two girls, and attempting to murder of 10 other babies at Countess of Chester hospital.

Nick Johnson KC, prosecuting, said she was a "constant malevolent presence" in the hospital's neonatal unit.

Ms Letby, 32, of Hereford, denies 22 charges at Manchester Crown Court.

Opening the prosecution case, Mr Johnson said the Chester institution was a "busy general hospital... like so many others in the UK".

However, he said that "unlike many other hospitals... within the neo-natal unit at the Countess of Chester Hospital, a poisoner was at work".

"Prior to January 2015, the statistics for the mortality of babies in the neo-natal unit at the Countess of Chester were comparable to other like units," he said.

"However, over the next 18 months or so, there was a significant rise in the number of babies who were dying and in the number of serious catastrophic collapses."

He said the increases were noticed by hospital consultants, who began an investigation.

"Having searched for a cause, which they were unable to find, the consultants noticed that the inexplicable collapses and deaths did have one common denominator," he said.

"The presence of one of the neonatal nurses and that nurse was Lucy Letby."

Mr Johnson told the court that as medics could not account for the collapses and deaths, police were called in and conducted a "painstaking review".

"That review suggests in the period between mid-2015 and the middle of 2016, somebody in the neonatal unit poisoned two children with insulin," he said.

"The prosecution say the only reasonable conclusion to be drawn from the evidence you will hear is that somebody poisoned these babies deliberately with insulin."

He said the deaths and collapses were "no accident" and were not "naturally-occurring tragedies".

"They were all the work... of the woman in the dock, who, we say, was the constant malevolent presence when things took a turn for the worse for these 17 children," he said.

The jury has been told the trial may last up to six months.