Perhaps not since Jack the Ripper prowled the streets of East London has there been a killer as depraved as Robert Napper. Yet his name is hardly known.

A flawed police fixation on criminal profiling that led to the jailing of an innocent man - Colin Stagg - for Napper's most notorious crime, the murder and mutilation of Rachel Nickell, denied the killer and rapist of his notoriety.

The full horror of Napper's five-year spree of violence, rape and death can now, however, be pieced together. He was the Green Chain rapist, terrorising as many as 86 women in a series of sex attacks which escalated from indecent exposure to the knifepoint rape of a mother pushing a pram.

He was the man who, when the police attention came too close, crossed London to attack and kill Ms Nickell as she walked on Wimbledon Common with her son, Alex, then aged two. As the boy watched, Napper stabbed his mother 49 times and mutilated her.

And he was the man whose maniacal rage reached a crescendo in November 1993 when he broke into Samantha Bissett's flat and stabbed her to death before sexually assaulting and smothering her four-year-old daughter Jazmine. He then cut open Miss Bissett's body with macabre precision.

Napper has admitted just six crimes - three killings, two rapes and an attempted rape - and refuses to discuss any further cases with police unless they can produce scientific proof of his guilt. Detectives will return to Broadmoor, where he has been detained since 1995, to question him about other offences.

His trademark was attacking young mothers accompanied by their children. Psychologists put it down to a childhood scarred by abuse and domestic violence, but detectives disagree and say Napper believed that women with children were likely to be more compliant to his demands.

Robert Clive Napper was born on February 25 1966 in a maternity hospital in Erith, south-east London, the first son of Brian Napper, a driving instructor, and his wife Pauline. His childhood was spent in a violent home until his mother sued for divorce when he was 10.

Mrs Napper's health deteriorated after the marriage break-up and all her children spent periods in foster homes. Robert truanted and shoplifted and was deeply damaged when, aged 12, he was sexually assaulted by a family friend on a camping trip.

The teenage Napper was a reticent, obsessively tidy, lonely boy who bullied his brother and spied on his sister as she undressed.

"Napper is a classic case of abuse meets neglect," says Professor Laurence Alison, author of a forthcoming book about the killer. "Trouble at school, disorder, petty crime - he's losing perspective, drifting away from reality."

After school he pursued a series of manual jobs, leaving home aged 21 to live in a bedsit in Plumstead, southeast London. The Green Chain attacks – so named because of the proximity of the incidents to the Green Chain walking route – began around the same time.

In November 1989, Pauline Napper phoned Plumstead police station to report that her son was claiming to have raped a woman on Plumstead Common.

Cursory checks were made and police told Mrs Napper they could not trace any such crime. Had the officers looked harder they would have discovered an unsolved inquiry into the rape of a 30-year-old woman in her home. The victim was attacked by a man with a knife while her children were at home.

Today the Old Bailey heard more details about his delusions and violent urges. Napper is a paranoid schizophrenic who believed he was untouchable and could transmit his thoughts by telepathy, the court heard.

Victor Temple, QC, for the prosecution, told the court that Napper had a "propensity to stalk and or seek out vulnerable young women not known to him with a view to rape, arming himself with a knife in order to intimidate and or control them.”

A psychiatrist who has been treating Napper in Broadmoor said that he also suffered from Aspergers’ Syndrome.

Natalie Pyszora said that Napper believed changes had been made to the calendar making him believe unusual things were taking place.

Dr Pyszora said that he was convinced he had an MA in maths and a Nobel Peace Prize and medals from fighting in Angola and he and his family were in Who's Who and that he may well have had millions of pounds in a bank in Sidcup, Kent.

Napper also believed that he could transmit thoughts through telepathy and had been kneecapped by the IRA and had had his fingers blown off by an IRA parcel bomb but they had miraculously grown back.

The psychiatrist said that his thought process was irrational and he would have felt untouchable at the time of the murder on Wimbledon Common.

She said she could not envisage Napper ever being let out of Broadmoor and that he accepted this, a sentence confirmed by the judge today.

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