Holly Evans, The Independent

For a mother whose newborn was gravely ill in the neonatal unit of the Countess of Chester Hospital, she was a ray of light: a calm, comforting nurse who guided her through her most desperate moments as her child lay listless in his cot. “Trust me, I’m a nurse,” she smiled at her, and the mother did, completely. But within hours, her baby boy was dead, and the nurse in whom she had placed so much trust, who had been by her side through the darkest time of her life, was responsible. The baby, identified only as Child E, was one of the victims of Lucy Letby, who has been found guilty of seven counts of both murder and attempted murder over the course of 12 months, from June 2015 to June 2016. She was found not guilty of two attempted murder charges, and the jury could not reach verdicts on a further six counts of the same charge.

Letby, 33, was not in the dock at Manchester Crown Court on Friday when the jury was discharged after deliberating for 22 days in a trial that has lasted 10 months. They found that she had killed or tried to kill the babies she should have been caring for — by injecting them with air, poisoning them with insulin, and overfeeding them with milk. But despite a lengthy trial that involved more than 240 witnesses, the families of her victims still have one haunting question left unanswered: why did she do it?

Throughout the trial, what has been notable is just how unremarkable Letby’s life was: a normal nurse who had a normal upbringing. “How I would describe her from my own experience in this investigation is ‘beige’,” deputy senior investigating officer DCI Nicola Evans said. “There isn’t anything outstanding or outrageous that we found about her as a person, in that she was an average nurse. “She was a normal twentysomething-year-old, doing what she was doing with her career, her friends. But clearly there was another side of that, that nobody saw.” Letby was brought up in Hereford as the only child of John and Susan Letby. She attended the local comprehensive and the family spent holidays in Devon. Jurors were shown pictures of her childhood bedroom, with two teddy bears placed on a duvet cover bearing the motif “Sweet Dreams”.

Framed pictures containing the slogans “Shine bright like a diamond” and “Leave sparkles wherever you go” appear on the bedroom walls, while a fluffy pink and white polkadot dressing gown hangs on the door. The images prompted a rare show of emotion, as Letby broke down in the dock. Moving 100 miles from home to study at the University of Chester, she was seen as a studious type, never staying out late. On qualifying as a registered NHS nurse in 2011, Letby developed a reputation among her colleagues as reliable, hard-working and trustworthy.

Two years later, she became the face of a campaign to raise £3m for the neonatal unit, and was a familiar sight in her neat uniform, her hair scraped back in a ponytail. The unit, and the staff within it, became her world, and she described her colleagues as her “family”. When asked in court, witnesses agreed that she had appeared professional throughout her time there, using words such as “knowledgeable” and “thorough” to describe her approach to work. Not short of friends, pictures of Letby on social media show a happy young woman enjoying life in her mid-twenties.

Holidays in Ibiza, enjoying party with friends to celebrate a win at the Grand National, and salsa classes with colleagues filled her social calendar. Shortly before she was moved from frontline duties in 2016, Letby travelled to Ibiza for a holiday with her girlfriends. Messages sent on 13 June showed a young woman groaning about packing and making jokes about Love Island.

Letby had joined her colleagues in appearing horrified at the apparent “run of bad luck” the neonatal ward was experiencing.

In reality, however, the alarm had been raised after the string of “inexplicable” deaths had caught the attention of consultants. While premature babies are often vulnerable, a number of sudden deteriorations and bizarre skin discolourations had pointed to something far more sinister.

As early as her third murder in June 2015, Letby was named as the “common denominator”, having been present at each incident.

Now found guilty of a total of seven murders and six attempted murders, Letby is one of Britain’s most prolific child serial killers, having taken advantage of the position of trust that she held to carry out a horrific campaign of attacks on the most vulnerable. “She abused the trust of the people around her, not just the parents who had trusted her with their babies but also the nurses she worked with, the people she regarded as friends,” said DCI Evans. “Lucy Letby was operating in plain sight.”