The parents of an extremely vulnerable newborn girl have said they were disgusted to find her “covered in her own faeces” while under the care of the nurse Lucy Letby.

The inquiry into the murder of babies at the Countess of Chester hospital heard that one child had been fitted with a stoma as well as a catheter, known as a Broviac line, after her birth in October 2015.

The girl, known as Child J, was considered to have a high risk of catching an infection after bowel surgery and had a series of unexplained and unexpected collapses on the hospital’s neonatal unit, the Thirlwall inquiry was told on Monday.

The child’s mother described finding her six-week-old daughter in a cot with her stoma removed and her lower half covered loosely with a soiled towel.

“I just took one look at her and was just disgusted really to see her in that situation, and also incredibly saddened being a mum in that situation thinking ‘what’s happened here?’,” she said.

The mother said it showed a “lack of care and humanity towards a child who was recovering from surgery” and was at “high risk” of becoming infected because of her Broviac line.

Child J’s father said the couple made a complaint the same day about their daughter being left “covered in her own faeces” but were told by the ward manager, Eirian Powell, that they were “tired and stressed and we should consider going home”.

He said they found this “quite annoying” and “condescending”. His partner added: “They didn’t really own what had happened. That was quite frustrating really – that it got turned – that it was us that were the challenge.”

Child J’s parents said they were never told the result of this complaint and learned only recently, eight years later, that Letby had been their daughter’s designated nurse on that shift on 15 December 2015.

Letby, who is serving a whole-life prison term after being convicted of murdering seven babies and trying to murder another seven, was charged with attempting to kill Child J but a jury was unable to reach a verdict following a 10-month trial at Manchester crown court last year.

The couple told Lady Justice Thirlwall that they had a series of concerns about their daughter’s care on the neonatal unit. They praised the consultants Dr John Gibbs and Dr Stephen Brearey but also said they were “stretched in their roles” and that the couple’s concerns had been dismissed by nurses.

Child J was born at the Countess of Chester hospital and transferred to Alder Hey hospital, in Liverpool, for bowel surgery, after which she returned to the Countess, the inquiry was told.

The parents contrasted the “meticulous attention to detail” at Alder Hey with their experience at the Countess, where they felt that Child J was not monitored as closely and sometimes even missed feeds because nurses were so busy.

Child J had been recovering well when she had a series of sudden collapses that doctors could not initially explain.

Letby, now 34, was later charged with causing one set of these collapses but jurors were unable to reach a verdict over the incident on 27 November 2015.

The parents told the inquiry that they refused to allow Child J to be taken back to the Countess of Chester hospital after she was taken to St Mary’s hospital in Manchester following another unexpected collapse in December 2015.

They said they had lived for years with a fear that Child J had an undiagnosed condition causing her to have life-threatening seizures because they had not been told the results of any investigation into her collapses.

Child J’s father told the inquiry it was “ludicrous and inconceivable” that Letby was moved to a role focused on patient safety in July 2016 despite concerns raised by colleagues that she may be deliberately harming babies.

Later, the mother of another newborn girl attacked by Letby demanded “accountability” from executives at the hospital.

Letby was found guilty of attempting to murder Child K after a retrial this year because jurors in the original trial were unable to reach a verdict.

The infant was born 15 weeks premature when the former neonatal nurse allegedly tampered with her breathing tube, causing a life-threatening deterioration. She was resuscitated and transferred to Arrowe Park hospital, Wirral, where she died three days later. Letby was initially charged with her murder, but prosecutors later decided there was insufficient evidence.

Child K’s mother told the inquiry hospital executives should have acted sooner when doctors raised concerns about the nurse. “They need to personally be accountable for it,” she said, adding that senior managers in other organisations would be “fined or put into prison” if they had failed to protect vulnerable lives.

She added: “For nobody to take accountability or ownership of that is not right because this will happen again.”