Prosecutors said Letby, 33, was a “calculated opportunist” who exploited the vulnerability of preterm and sick infants to cover up her actions.
In 2015 and 2016, the Countess of Chester Hospital’s neonatal unit saw a significant increase in the number of babies who suffered severe and unexpected collapse.
Letby was the only member of the nursing and clinical staff who was on duty whenever there were breakdowns, which the Crown did not believe were natural events.
She used various methods to harm the babies, including injecting air into the bloodstream, injecting air into the stomach, overfeeding milk, physical assault, and insulin poisoning.
Some of the children have been subjected to repeated attempts to kill by the Band 5’s “cold, cruel and unrelenting” nurse, the trial, which began at Manchester Crown Court last October, has revealed.
Letby’s presence at breakdowns was first mentioned by the unit’s chief adviser to senior management in late June 2015.
Concerns from some advisers about the defendant grew and were voiced to hospital bosses amid more unexplained and unusual collapses, the court heard.
But Letby was not released from the unit until June 2016, when two triplets died and another young boy collapsed for three consecutive days.
Restricted to clerical work, Letby filed a grievance procedure in September 2016.
During the legal argument at the trial – in the absence of the jury – it turned out that the appeal proceedings in December 2016 were decided in Letby’s favour.
Letby was due to return to the neonatal unit in March 2017, but the move didn’t take place once police were contacted by the hospital administration.
The nurse was arrested at 6am on 3 July 2018 at her semi-detached houses in Westbourne Road, Chester.
A search of her address uncovered several closely written notes.
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On a green Post-it, she wrote: “I don’t deserve to live. I killed her on purpose because I’m not good enough to take care of her”, “I’m a terribly bad person” and in capital letters “I’m bad, I did that”.
Prosecutor Nick Johnson KC asked the jury to read the note “literally” as a confession.
Searches, the court learned, also found more than 250 shift handover sheets containing the names of some of the children named in the indictment.
Mr Johnson said “voyeuristic tendencies” had prompted her to conduct numerous Facebook searches for parents of the children she attacked.
The “rogue nurse” falsified medical records to cover her tracks and also pressured doctors and nurses to convince them the breakdowns were “just bad luck”.
She is also willing to publicly slander colleagues’ reputations “to get away with it,” the prosecutor added.
Letby, from Hereford, denied all allegations.
The jury of seven women and four men returned partial verdicts as Judge Goss issued a ban on reporting until their deliberations were complete.
On August 8 — the 15th day of deliberation — the jury unanimously found her guilty of attempting to murder two infants by insulin poisoning.
Letby fought back tears in the middle of the dock after the jury foreman announced the verdicts.
She broke down in tears as she walked out of the courtroom with the prison officials while the victims’ families looked on from the bleachers.
Her mother Susan, 63, shielded her face while she cried across the public gallery and was comforted by husband John, 77, who later leaned forward with his head in his hands.
As deliberations began on the afternoon of August 11, the jury announced its verdicts on a further six counts.
Letby was found guilty of murdering four babies and attempting to murder two others.
READ MORE: Nurse arrested again over deaths of eight newborns in hospital
She stared at the floor as the verdicts were announced but cried as she left the dock.
Her mother could be heard sobbing and saying, “You can’t be serious” and “That can’t be right.”
On August 16, the jury convicted her of six more counts — three murders and three attempted murders — and acquitted her of one count of attempted murder.
The grandmother of Child G, a little girl, gasped when Letby was found guilty of attempted murder of the infant.
Letby did not sit in the dock when the above sentences were announced because she did not want to leave the cells. She was present when the jury resumed its deliberations at the beginning of the court day.
The morning of August 17 was her final courtroom appearance when she told her legal team that she no longer wished to attend the trial.
She was offered the opportunity to watch the sentencing hearing via prison video, but said she was unwilling to do so, the court learned.
In six counts of attempted murder, the jury failed to reach a verdict.
Cheshire Police say they continue to review the care of around 4,000 babies admitted to the Countess of Chester – and also to Liverpool Women’s Hospital when Letby completed two internships – during her tenure from 2012.
Only the medically questionable cases would be further investigated, the police added.
A court order prohibits disclosure of the identities of the surviving and deceased children who were the subject of the allegations.