Families seek answers after British nurse Lucy Letby convicted of killing seven newborns

Letby, who was in her 20s at the time of the murders, is the most prolific child serial killer in modern British history.

Her case has captivated Britain after she was put on trial for the killings and attempted murders in the neonatal unit of a hospital in northwest England where she worked.

Following her conviction at a court in Manchester in northern England on Friday, the families released a joint statement saying they would never truly know why this had happened.

"To lose a baby is a heartbreaking experience that no parent should have to go through," they said. "But to lose a baby or have a baby harmed in these circumstances is unimaginable."

The families cannot be named for legal reasons. The parents of twin boys who Letby tried to murder revealed the turmoil that they had been through, going from the euphoria of the birth to the horror of seeing staff fight to keep their children alive.

They did not realise what had happened until the police contacted them about two years later.

"It didn't have to be that many," the father told Sky News, asking why hospital bosses had not acted sooner to stop more babies from being attacked. He said he felt "very let down" by the hospital.

Letby was present at the birth of the two boys and the parents said they were ecstatic at being first-time parents.

But the mother realised something was wrong when another nurse came into her room, saying she needed to come downstairs. The father said he remembered seeing the doctors pumping his child's heart "like a rag doll".

"I was just full of tears," he said. "We didn't know what was going on." He remembered how other nurses looked "very worried and panicked" while Letby was standing "very calm and cool".

Both the twins survived, but one suffered some brain damage and his parents worry it might impact him in the future.

The boys' father said he is now a "changed person" and suffers sleepless nights and depression.