The mother of a 13-year-old girl who was murdered by a known sex offender condemned the criminal justice system yesterday after it emerged that a catalogue of blunders had let him live unknown in her community.

Timothy Cuffy, 38, who was obsessed by knives, slit Sandy Headfield's throat when the authorities, who were meant to be watching him after he left jail, lost track of him.

Despite being a Schedule One offender ? one known to pose a risk to children ? he was allowed to change his name and move cities, giving several agencies the slip. Twice he even came into contact with the police, but still nothing was done.

Yesterday, after an official report slammed the handling of Cuffy's case, Sandy's mother, Jackie James-Clarke, 37, said: "I have never met such a bunch of so-called professional people who are so unprofessional.

"We had no idea of the type of person Cuffy was, and the fact that he could be out on the streets after everything he had done is frightening.

"Letters were lost, and people didn't do their jobs. I feel very badly let down by the criminal justice system. How can I now have any faith at all in the system again after what has happened?"

Cuffy, from Derby, used a kukri given to him by a historical re-enactment society to kill Sandy after leading her to her "execution" in July 2002.

He plied the youngster with drink until she was "literally legless" then took her to a secluded spot in Boultham Park, Lincoln, to kill her.

He later returned to the scene on his bicycle, dialling 999 and claiming to have stumbled across her body.

His trial in 2003 heard he was fascinated by knives and the Brazilian "death-metal" group Sepultura, whose name means "grave" in Portuguese.

He had the insignia of the band, whose songs include Murder and Cut-Throat, on his T-shirt, which was stained with Sandy's blood.

After a jury convicted him of the "ritualistic" murder, it was revealed that Cuffy had been jailed for a string of attacks on women and girls.

Thirteen years ago he assaulted a 16-year-old and in 1997 he was jailed for six years after assaulting a deaf woman.

Cuffy, now 38, was released from that sentence in October 2000 and within months had moved to Lincoln under the name Timothy Barnett.

Agencies in Derbyshire didn't know he had left, agencies in Lincolnshire didn't know he had arrived, and even police failed to recognise him when he claimed that a woman had racially abused him. Once he told parents at an infants' school attended by a girlfriend's child that a man was approaching pupils and stalking them.

His allegations resulted in police involvement and an assembly to warn youngsters about "stranger danger".

Yesterday's independent report, produced by the Lincolnshire Safeguarding Children Board, admitted that the authorities had "lost sight" of him. It said: "His Schedule One status should not have been lost sight of. It should have been communicated and followed through." The report said it was "imperative" that police, the probation and prison services "liaise closely" in such cases.

In an apparent reference to the Soham murderer Ian Huntley, who changed his name when he moved from his native Humberside to Cambridgeshire to prevent the authorities knowing about his past, he said: "In some notable cases nationally in recent years ... the ability of agencies to monitor and track such individuals can be seriously called into question."

The report urged that its findings be brought to the attention of the Home Office and public protection ministers "as a matter of urgency".

Mrs James-Clarke, 37, who has four other children, said the inquiry revealed many things she had been unaware of during her ordeal.

She said: "When something like this happens you want to know how, why, what and when. Your mind can't rest until you know what happened. You can't start the healing process until you know the facts. But it was three months after Sandy died before I even learned how she was killed."

She said a police officer had arrived at her house on her birthday and, in front of her children, told her in graphic details how her daughter was killed. She said: "They should not have had to hear that. In the end I ordered the officer out of my house."

She said the authorities had not kept in touch with her throughout the development of the investigation and court case, adding: "It turns out things were done wrong from day one. The report has told me a lot of things I didn't know."