The serial killer nurse, Lucy Letby, will never be released from prison after she was sentenced to a rare whole-life term for the “sadistic” murders of seven babies. Letby, who is Britain’s worst child serial killer, refused to leave the court cells as the parents of her newborn victims described the horrifying impact of her crimes. One bereaved mother called Letby’s absence “one final act of wickedness from a coward”. A father, sobbing, said the murder of his two identical triplet sons had torn his family apart, leaving him suicidal and ruining their trust in medical professionals. “It has destroyed me as a man and as a father,” he said. Letby, 33, became only the third woman alive to be handed a whole-life jail term as she was sentenced for murdering seven babies and trying to kill another six. A number of her surviving victims have been left with life-changing disabilities, Manchester crown court was told. One girl, now seven, is blind and has been diagnosed with quadriplegic cerebral palsy. She is nil-by-mouth and requires major spinal surgery. Her father described how his daughter was born 15 weeks early, weighing 535g (1lb 3oz) and given just a 5% chance of survival. He told told the court that “God saved her” but then “the devil found her”. The judge, James Justice Goss KC, described Letby’s crimes as a “cruel, calculated and cynical campaign of child murder involving the smallest and most vulnerable of children”. He added: “There was a deep malevolence bordering on sadism in your actions. During the course of this trial you have coldly denied any responsibility for your wrongdoing and sought to attribute some fault to others. You have shown no remorse. There are no mitigating factors.” Letby’s 10-month trial heard how she often attacked the infants moments after their parents or nurses had left their sides. She fatally injected seven babies with air, tried to kill two others by lacing their feeding bags with insulin and attempted to murder one by thrusting a nasogastric tube down his throat. The judge said the nurse had shown a “detached enthusiasm” for the resuscitation of babies she had harmed and that she “cruelly and callously” made inappropriate remarks to parents or colleagues during or after a death. She kept hundreds of medical documents as “morbid records of the dreadful events surrounding your victims and what you had done to them”, Goss said. The motivation behind the murders is unclear and may never be known. The prosecutor, Nicholas Johnson KC, told the trial that Letby enjoyed “playing God” and was “excited” by the drama when doctors rushed to save the days-old babies she had attacked. Goss said she appeared to take a particular interest in twins – three pairs of twins and one set of triplets were among her 13 victims – and in babies who were born with vulnerabilities. However, the judge said it was not for him to “reach conclusions about the underlying reasons” for Letby’s actions. “Nor could I,” he added. “For they are known only to you.” The mother of twin boys, one of whom was murdered and the other Letby poisoned with insulin, told the court Letby was a coward for failing to attend the sentencing hearing. She said their world had been “shattered when we encountered evil disguised as a caring nurse,” and she added: “We have attended court day in and day out, yet she decides she has had enough, and stays in her cell – just one final act of wickedness from a coward.” A law firm representing the families of seven of Letby’s victims described her refusal to appear in court as “the final insult”. “By not facing the consequences of her actions, it speaks of her complete disregard not only for the damage she’s caused, but also to our judicial system,” said Tamlin Bolton, a solicitor for law firm Switalskis. Alex Chalk, the justice secretary, said Letby had taken “the coward’s approach” by refusing to appear in the dock on Monday. Chalk said ministers were looking to change the law “at the earliest opportunity” to require that “the worst offenders attend court to face justice, when ordered by the judge”. Whole-life orders, like the one handed to Letby, are reserved for crimes of exceptional gravity. The other two women serving whole-life terms are Rose West, who tortured and killed at least nine young women in the 1970s and 1980s, and Joanna Dennehy, who murdered three men in what came to be known as the Peterborough ditch murders in 2013.