A mother “completely trusted” nurse Lucy Ms Letby when she left her screaming son in her care, a court has heard.
Ms Letby, 32, is said to have murdered the infant with an injection of air into the bloodstream.
The Crown says she attacked the newborn baby, referred to as Child E, shortly before his mother walked into the intensive care room of the neonatal unit at the Countess of Chester Hospital.
Giving evidence on Monday, Child E’s mother told jurors at Manchester Crown Court she visited the unit just before 9pm on 3 August 2015 to drop off breast milk.
Her son and his twin brother, Child F – whom Ms Letby is accused of later attempting to murder – were in incubators in the room with Ms Letby, she said.
Prosecutor Nick Johnson KC asked: “What could you see and hear when you walked into the room?”
It was a sound that should not come from a tiny baby. I can't explain what the sound was. It was horrendous. More of a scream than a cry— Child E’s mother
She replied: “I could hear my son crying and it was like nothing I had heard before. And I walked over to the incubator to see blood coming out of his mouth.
“And I panicked… I was panicking… because it felt there was something wrong.”
The witness recalled Ms Letby was standing at a nearby work station when she entered the room.
“She was busy doing something but was not near [Child E],” said the boy’s mother.
She told the court she heard the cries in the main corridor as she approached the room.
She added: “It was a sound that should not come from a tiny baby. I can’t explain what the sound was. It was horrendous. More of a scream than a cry.”
The mother explained she tried in vain to comfort her son and then noticed blood around his bottom lip and the top of his chin.
Mr Johnson asked: “Did you ask Lucy Letby about what it was you could see?”
The witness replied: “Yes. I asked why he was bleeding and what was wrong.
I knew there was something very, very wrong. I was frightened— Child E’s mother
“She said the feed tube from the back of his throat would have been rubbing and that would have caused the bleeding.”
Mr Johnson said: “Did you accept that explanation?”
“Yes,” said the witness.
Mr Johnson said: “Were you concerned about the explanation?”
“Yes,” repeated the witness.
Mr Johnson asked: “Did Lucy Letby say anything else to you?”
Child E’s mother said: “She told me to go back on the ward.”
Mr Johnson said: “Did you do what you were told?”
“Yes,” said the witness.
Mr Johnson went on: “Why?”
The boy’s mother said: “Because she was an authority and she knew better than me and I trusted her. Completely.
“She said the registrar was on the way and if it was a problem someone would ring up to the post-natal ward.”
She said when she returned to the ward she phoned her husband.
“I knew there was something very, very wrong. I was frightened,” she said.
She said she was “panicking” but was “following the rules” in waiting for any update.
She told the court: “The rules were, go back upstairs and if there was a problem I would call you, and that was Lucy Letby on the neonatal unit. I followed those rules.”
The witness later cried as she told jurors: “I knew. I knew there was something wrong and I had known from leaving him but I left.”
Child E later deteriorated and his mother was later brought back to the unit where she sat outside in the corridor as medics unsuccessfully attempted to resuscitate him.
Ms Letby, originally from Hereford, denies the murders of seven babies and the attempted murders of 10 others between June 2015 and June 2016.
