Former British nurse and convicted child serial killer Lucy Letby on Thursday lost an attempt to appeal against her conviction for trying to murder a newborn baby, amid questions over the fairness of her trials.

Letby, 34, was found guilty of murdering seven children and attempting to murder seven more between June 2015 and June 2016 while working in the neonatal unit of the Countess of Chester Hospital in Chester, northern England, making her Britain’s worst serial child killer of modern times.

She was convicted of an eighth count of attempted murder at a retrial earlier this year, after the original jury was unable to reach a verdict on a charge that Letby tried to kill a baby girl by removing her breathing tube.

Prosecutor Nick Johnson told Manchester Crown Court that, little more than an hour after the child was born, a senior doctor found the baby’s breathing tube dislodged and Letby standing there “doing nothing.”

Letby’s lawyer Benjamin Myers told London’s Court of Appeal on Thursday that Letby “maintains and has maintained she is not guilty of the offenses.”

He argued that the retrial was an abuse of process as Letby could not have a fair trial because of extensive coverage of her convictions, which featured “intense hostility towards her” and comments made by the Crown Prosecution Service and police.

“There was no way in which the jury in trial two were going to have the publicity and the comment and the hostility ameliorated,” Myers said.

Judge William Davis refused Letby’s application for leave to appeal against the conviction from her retrial.

Letby attended the hearing by videolink from prison and sat impassively as the judge stated the court’s reasons for refusing her application.

“The outcome of the first trial undoubtedly led to an unusually large amount of publicity and online debate,” Davis said. “That is because, on its face, the case was extraordinary.”

Letby’s attempt to overturn her convictions from the first trial was refused in May. She can now only challenge those convictions if the Criminal Cases Review Commission refer those cases back to the Court of Appeal.

Since her trials, Letby’s conviction has come under a spotlight, following criticism by some experts of medical and statistical evidence presented by the prosecution.

Some media have questioned whether she might be the victim of a miscarriage of justice, while a public inquiry into her crimes continues.