Child serial killer nurse Lucy Letby told a colleague more than a year before her arrest she was worried she had “maybe done something wrong” to babies, an inquiry has heard.

Letby expressed her concerns in an email to an occupational health nurse in April 2017 and added: “I blame myself”.

Kathyrn de Beger told the Thirlwall Inquiry into events surrounding the crimes of Letby that bosses at the Countess of Chester Hospital gave her the task of supporting the nurse’s mental health and wellbeing following her removal from the neonatal unit in July 2016.

She said she was initially informed that Letby had been redeployed for training purposes amid a probe into an increased mortality rate on the unit but later learned she was suspected of causing harm to patients.

A WhatsApp group was set up with Letby, her union representative Hayley Cooper, Ms de Beger and Karen Rees, head of nursing in the urgent care division, the inquiry heard, with hundreds of messages sent including discussions on Letby’s shopping trips to Liverpool, a forthcoming family wedding and cookery tips.

Ms de Beger said: “I have not been in a WhatsApp group with any other member of staff but I’ve not supported staff in this situation ever before and I felt at that time that I was the only support that Lucy Letby had.

“She was going through what I thought at the time was a very distressing situation and it was given to me to support her the best I could, to keep her in work and maintain her mental health.

“That’s why there were so many messages to try to make sure she was OK.”

The inquiry heard Ms de Beger stated to police that Letby asked for meetings with her around the anniversaries of babies’ deaths but in her evidence she said she thought this happened just once.

She told counsel to the inquiry Andrew Bershadski that no other members of staff had ever asked for such meetings.

Mr Bershadski said: “Is it right, therefore, that Lucy Letby being distressed around the anniversaries of the babies’ deaths was unusual compared to other nurses you were supporting on the unit at the time?”

Ms de Beger replied: “‘She spoke about being particularly distressed that week because she recalled it was the anniversary of one of the babies’ deaths but then we were having a meeting about managing her feelings and symptoms and talking about coping strategies.

“It was in the context that she was feeling particularly distressed but how much more would the parents feel at the loss of their baby. That’s how she framed it.”

In an email discussion in April 2017 Letby told Ms de Beger: “I feel as though this must be my fault and have maybe done something wrong to babies and I blame myself, do you think that’s normal?”

Ms de Beger said the remark did not raise concerns as Letby had previously always told her she had done nothing wrong.

She said: “At that time I believed mediation between the clinicians and Lucy Letby had broken down and she was very distressed about that.

“There was a plan for her to return to the neonatal unit at the beginning of April but that was postponed and she was very upset about that. I do remember at this time that she was very, very distressed, very confused.

“So I felt that it was an explanation of all those mixed emotions and that’s what I replied to her.”

Police were called in to investigate in May 2017 and Letby was first arrested at her home in Chester in July 2018.

Dr Joanne Davies, consultant clinical lead in obstetrics and gynaecology in 2015 and 2016, told the inquiry that before the death of two triplet boys in June 2016 there was “a general feeling that was something not right with the NNU as we had previously had such low mortality rates”.

She said: “There were rumours among the obstetric and midwifery staff, and there was an occasional unfounded comment that we had ‘another Beverley Allitt’.

“We were always quick to stop this gossip as it felt completely unthinkable.”

Allitt murdered four children and harmed nine others when she worked as a nurse at Grantham Hospital in Lincolnshire in 1991.

The inquiry is expected to sit at Liverpool Town Hall until early next year.