Ian Huntley, 29, was the caretaker at Soham Village College, on the same site where Holly and Jessica went to primary school.
When the girls disappeared, Huntley was going out and living with Maxine Carr - who was a teaching assistant in Holly and Jessica's class.
He joined in the search for the girls when they went missing and told police he had seen them on the day they vanished. It soon became clear he was one of the last people to have seen them alive.
He was arrested on 17 August 2002, and on 20 August he was charged with both their murders.
During a high-profile court case, which started over a year later on 3 November 2003, Huntley admitted the girls had died in his house.
He said Holly died accidentally when she fell into the bath, and he killed Jessica without meaning to when he put his hand over her mouth to stop her screaming.