In 1993, staff at a UK hospital became suspicious of the amount of deaths from cardiac arrests in the children's ward. An investigation began, and police learned that Beverly Allitt was the nurse on duty at the time of each death. Toxicology tests revealed these deaths weren't accidental – Allitt had been injecting the children with toxic amounts of potassium chloride and insulin to cause cardiac arrest or lethal hypoglycaemia. She was found guilty and given 13 life sentences.