A hospital nurse accused of murdering seven babies was interrupted by one of her victim’s mothers as she was fatally attacking her newborn son, prosecutors say.

Lucy Letby allegedly killed Child E by an injection of air into the bloodstream while working at the neo-natal unit at the Countess of Chester Hospital, Manchester Crown Court heard.

Prosecutor Nick Johnson KC said that on the evening of 3 August 2015, Child E’s mother visited her son in the unit.

Mr Johnson said: “We say that she interrupted Lucy Letby who was attacking (Child E), although she did not realise it at the time.”

When the mother arrived, her son was “distressed” and bleeding from the mouth, the court heard.

The mother recalled Letby tried to reassure her, he said, and told her a registrar would review the youngster’s condition and she should leave the unit.

“‘Trust me, I’m a nurse’. That’s what she told (the mother),” said Mr Johnson.

“We suggest she was fobbed off by Lucy Letby.”

Child E went on to suffer significant blood loss, say the Crown, later in the evening, with a treating registrar saying he had never encountered such a large bleed in a small baby.

Following Child E’s death in the early hours of 4 August, the Crown said Letby made “fraudulent” nursing notes which were “false, misleading and designed to cover her tracks”.

Letby, 32, denies seven counts of murder and 10 counts of attempted murder.

The second day of the prosecution opening at court also heard how Letby went on to show “very unusual interest” in Child E’s family and the families of her other alleged victims.

Mr Johnson said she carried out social media searches on Child E’s family two days after the youngster’s death and again on numerous occasions in the following months, including “even on Christmas Day”.

Jurors heard how the day after allegedly murdering Child E, Letby allegedly used insulin for the first time to poison a baby by trying to murder child E’s twin brother, child F.

Child F was prescribed a TPN (total parenteral nutrition) bag of fluids and later suffered an unexpected drop in his blood sugar levels and surge in heart rate. Checks on his insulin levels were carried out which showed, “conclusive evidence” someone had given child F insulin to poison him.

Mr Johnson said no other baby on the neo-natal unit was prescribed insulin so child F could not have received the drug intended for some other child by negligence.

Mr Johnson said the prosecution allege Letby had injected insulin into the TPN bag before it was hung up to give to the child.

He added: “You know who was in the room and you know from the records, who hung the bag.

“It can’t have been an accident.”

Prosecutors earlier alleged Letby murdered a five-day-old baby by injecting air into his stomach through a nose tube.

She allegedly killed the baby boy, Child C, just six days after murdering for the first time, when she killed another baby boy, Child A, and days later attacked Child B.

Child C died because the air injected into his stomach made him unable to breathe and he suffered a cardiac arrest, Mr Johnson told the jury.

The boy had been born prematurely at 30 weeks on 10 June 2015 weighing only 800 grams, but despite going into intensive care was in good condition.

Five days later, on the nightshift of 14 June, Letby was supposed to be looking after another, more poorly baby, in another room.

But she was the only person in the room when Child C suddenly and unexpectedly collapsed.

Mr Johnson said an independent pathologist – when reviewing the case – concluded Child C died because his breathing became compromised and he suffered a cardiac arrest.

The prosecutor told jurors: “If you are trying to murder a child in a neo-natal unit, it is a fairly effective way of doing it. It doesn’t really leave much trace.”

He said on the afternoon of 14 June, 2015 – hours after Child C died – the defendant searched on Facebook for the youngster’s parents.

Mr Johnson suggested from the timings that this was “one of the first things she did when waking up” after she had earlier finished her shift at about 8am.

He then moved on to detailing the death of Child D, who the Crown say was murdered by Letby with an intentional injection of air into the bloodstream.

Letby sent “many messages” to friends in the wake of Child D’s death and the preceding deaths and collapses in which she suggested they could all clearly be explained as natural causes.

The defendant later told police she could not explain why she had searched on Facebook for Child D’s parents in the aftermath of her death.

She was also asked about another message in which she had referred to an “element of fate” being involved.

Mr Johnson told the jury: “We say, tragically for (Child D) her bad luck or fate was the fact that Lucy Letby was working in the neo-natal unit that night.”

The trial continues on Wednesday.