Robert Napper was a loner and fitness freak who had been sexually abused when he was 10 years old and went on to become a serial sex offender and killer.

He left home at 17 and was obsessed with washing his bed linen to conceal evidence of sexual activity. The former Ministry of Defence worker, who suffers from Asperger's Syndrome and paranoid schizophrenia, was also a fan of military and survival magazines.

He was said to be an obsessive Peeping Tom who kept notes on the women he stalked and fantasised over.

His confession to the manslaughter of 23-year-old model Rachel Nickell yesterday, on the grounds of diminished responsibility, brought to an end a 16-year police investigation which has been riddled with blunders and missed opportunities.

Napper, who confessed to the killing of Samantha Bissett, originally from Dundee, and her daughter Jazmine, at a trial in 1995, is thought to be responsible for 106 sex attacks across southeast London by the so-called Green Chain Rapist during the late 1980s and early 1990s.

He was obsessed with knives and death and has previously admitted sexually assaulting three young women in the months before Ms Nickell, a mother of one, was killed.

Two months later Miss Nickell, who was brought up in Great Totham, near Colchester, Essex, was targeted as she walked on Wimbledon Common with her two-year-old son, Alex, and their dog.

But Napper was not linked to the extensive police inquiry, and on November 3, 1994, he murdered Ms Bissett and her daughter at their home in Heathfield Terrace, Plumstead.

Napper, who at the time of the murders was working at a plastics factory in the same area, was suspected of spying on Ms Bissett with her boyfriend before climbing into the basement flat.

He assaulted Ms Bissett and stabbed her eight times in the neck in the hallway, before sexually assaulting and suffocating Jazmine in her bed.

Napper, who was over 6ft tall, then dragged Ms Bissett's body into the living room, where he mutilated her.

Such was the brutality of the attack that the police photographer at the scene was off sick for two years.

Although Napper left his bloody fingerprints in the flat, it was not until May 1994 that they were traced to him. By then he had been arrested and discharged for shoplifting.

Although both Samantha and Rachel were blonde, murdered in the presence of their young children and the victim of horrific knife injuries, the police view, backed by criminal psychologist Paul Britton, was that the killings were not linked.

The Metropolitan Police had instead targeted Colin Stagg, an unemployed man known to walk his dog on Wimbledon Common who was targeted in a heavily criticised sting operation.

Between May and September 1994, both Napper and Mr Stagg were in custody, but police decided not to investigate similarities between the Bissett and Nickell murders until the end of court proceedings. A police photofit released at the time of the Nickell killing bears a striking resemblance to both men.

The police investigations coinciding with Napper's assaults and murders contained a catalogue of errors which may have prevented some or all of the killings.

The serial killer's name was first provided to police in November 1989, after a tip-off from his own mother. She rang Plumstead police station claiming he had told her he was responsible for a rape on the nearby Common.

An officer searched the paper files and computer system but failed to link it to a sex attack on a woman in Plumstead on August 10, 1989.

Napper was only linked to that rape by his DNA profile in July 1994. It was not proceeded with at court because of a scientific blunder known as "transposition".

By then, he was already under arrest for the Bissett murders.