My God I've got to ring her in

"Mary Bell was standing in front of the Howe's house when the coffin was brought out. I was, of course, watching her. And it was when I saw her there that I knew I did not dare risk another day. She stood there, laughing. Laughing and rubbing her hands. I thought, My God, I've got to bring her in, she'll do another one."
- Detective Chief Inspector James Dobson, Newcastle Police
(Robert Musel, United Press International, March 1975)
On hearing of Mary’s arrest, her schoolteacher, Eric Foster, looks over his troubled pupil’s exercise books. He finds that Mary has made notes about Martin’s death and drawn pictures which contain information about the murder scene that was never revealed to the public. There was only one explanation: Mary was there when the little boy died.

The investigation has identified an eye-witness, the killers themselves have left clues to their identity on their victim's body and there are confessions to Martin’s death in childishly scrawled notes. Forensic evidence also finds fibres from the victims on both Mary and Norma’s clothing.
The girls deny any involvement in the crimes; the detectives are amazed at Mary’s intelligence and agile mind. She would answer one question and correctly anticipate the further series of questions from police and give answers to those as well.
Chief Inspector Dobson formally charges Mary Bell with the murder of Brian Howe. "That's all right with me," she replies. He then charges Norma Bell, who in anger at the charge, declares, "I never. I'll pay you back for this."
The first night in their small jail cells, the girls are restless. The police station is not accustomed to housing such young offenders.