Chilling recording shocked the court

The chilling sound of 10-year-old Lesley Ann Downey's own voice, pleading in vain for mercy from her tormentors, convinced hardened detectives and jurors alike of the sadistic nature of the Moors murderers.

As she was being tortured to death by Ian Brady and Myra Hindley, the little girl's cries were being taped by Hindley in a recording that no one who heard it will ever forget.

There was not a murmur or cough in the oak-panelled court in Chester Castle at the killers' trial in 1966, as Lesley Ann could be heard crying out.

The tape ran for 16 minutes, during which women in the public seats at the back of the court put their hands over their ears. One wept openly.

The sound of the girl being tortured was accompanied by Christmas music being played in the background, including the song Little Drummer Boy by Ray Conniff and his singers. As the music played in the courtroom Brady, wearing a grey suit, unwrapped a packet of mints and put one in his mouth.

During the playing of the tape, Hindley, dressed in a grey tweed suit, blue-striped blouse and white shoes and sitting with Brady in the dock behind a screen of bullet-proof glass, showed no sign of distress and pulled a handkerchief from her pocket to blow her nose.

The pair were already notorious, with 150 reporters queuing for access to the courtroom.

John Stalker, former deputy chief constable of Greater Manchester, who was then a detective sergeant, expressed the feelings of many when he said of the tape: "Nothing in criminal behaviour before or since has penetrated my heart with quite the same paralysing intensity."