KEY POINTS:
In November 1989, Pauline Lasham told the Metropolitan Police her son had confessed to a rape two months earlier on Plumstead Common, southeast London. She was right. Her son, Robert Napper, had raped a woman - the first of an estimated 106 sexual assaults he would commit.
But his mother got one bit of information wrong. The attack was not on the common, but in a house nearby.
Lacking this piece of information, the police found no record of the crime and did not act on the tip. Three years later, in 1992, Rachel Nickell was murdered. The police's failure to act in 1989 was the first of six chances they had to arrest Napper. But they missed every one. So Napper went on to rape and kill Samantha Bisset, 27, and her 4-year-old daughter Jazmine in November 1993.
Robert Clive Napper was born in February 1966 in Erith, southeast London, to Brian Napper, a driving instructor, and his wife Pauline.
His childhood was marred by violence between his parents and he was sexually abused by a family friend when he was 10. As a teenager, Napper was a reticent, obsessively tidy, lonely boy who bullied his brother and spied on his sister as she undressed.
After school he pursued a series of manual jobs, leaving home aged 21 to live in a bedsit in Plumstead. His workmates considered him dull and boring: he turned up on time and did not speak much.
But undetected by his colleagues and later, the police, his sexual deviancy became extreme. It started with flashing and voyeurism, then escalated to rape and finally murder.
Before he killed Nickell, Napper was suspected of four rapes, and he has since been convicted of three of them. Those rapes were part of a series of 106 sexual assaults known as the Green Chain rapes, in south London in the early 1990s near where he lived.
Although Napper has admitted his involvement in four of them (one never got to trial), it is suspected, he may have committed all of them.
Apart from his mother's suspicions, which were never acted on, there were five other occasions when police could have apprehended Napper. The first came in August 1992, a year before the Bisset killings and a month after Nickell's when an computerised image of the Green Chain rapist was issued and a neighbour and work colleague alerted the police to Napper.
Officers asked him to visit a police station on September 2 1992 and give a DNA sample, but he never turned up. The following day, he was again identified as the man in the image by a caller who identified him as "Bob Napper". Again police visited and asked him to attend a police station to give a sample. An appointment was scheduled for September 8 1992, but again he failed to turn up.
Despite his unwillingness to provide the police with DNA, knowing it would match samples found on the three rape victims, Napper was then ruled out of the rape inquiry simply because he was 1.88m and police believed the man they were looking for was 1.75m.
Three days later he was arrested for possession of a firearm and sentenced to two months in prison. In April 1993, a pistol with his fingerprints was found on Winns Common, south London, yet police did not pursue him for this. Seven months later, he murdered Samantha and Jazmine Bisset.
Commander Simon Foy, of the Metropolitan Police, admitted police errors had contributed to the death of the mother and her daughter.
"If any of these opportunities had been taken, it is probable that he would have been in custody and would not have murdered Samantha and Jazmine," he said.
"We have been absolutely honest about this to Samantha and Jazmine's family and we have told them that we deeply regret that this happened and have apologised to them."
But despite the same sickening brutality in the murders of the Bissets and Nickell, officers did not see a link and continued with the wrongful prosecution of Colin Stagg for Nickell's murder.
Stagg had been charged in August 1993, two weeks before Samantha and Jazmine Bisset were killed, and went on trial the following year.
But he was acquitted in September 1994 after the judge, Mr Justice Ognall, condemned the police tactics used to arrest and prosecute him.
These included the honeytrap set up by the police in which an undercover officer contacted Stagg, who was awarded compensation of 735,000 ($1918,000) earlier this year, and encouraged him to fantasise about sex and violence.
The judge threw out the case saying that the police were guilty of "deceptive conduct of the grossest kind".
Now the police were back to square one. It was only a chance misprint in a London A to Z that led the Nickell investigation on Napper.
Napper was charged with the Bisset murders in May 1994 after his fingerprints were found at the scene. After searching his flat, police found two London A-Zs with certain locations marked in pen by Napper. These correlated to where he had committed the two murders, one rape and two attempted rapes that he would plead guilty to in October 1995.
One of the markings was on Wimbledon Common, leading officers to suspect he had perhaps murdered Nickell, too. But the mark was not made by Napper: it was a printing error by the manufacturer.
Nevertheless, officers decided to visit Broadmoor mental hospital and interview Napper about the Nickell case in December 1995. He refused to answer questions, telling the police he would only discuss his involvement in the case if they had forensic evidence to link him to the crime. They did not.
But in 1999 more sophisticated DNA techniques were developed, and the forensic teams began work on identifying fibres and hair, found on Nickell's body.
Eventually, in November last year, a positive DNA match from the body to Napper was found. He was charged with the murder in December last year and this week admitted killing Nickell stabbing her 49 times, raping her and leaving her under a tree on Wimbledon Common in July 1992.
As well as the crimes to which he has confessed, Napper is suspected of committing 106 rapes and sexual assaults in the five years before he was caught.
Police now believe Napper was the notorious Green Chain rapist who stalked women in southeast London in the early 1990s.
Detectives have identified 106 incidents involving 86 women for which they believe he is responsible.
Police will re-interview Napper in the hope that he will confess to these crimes, but again demanded forensic evidence to link him to it.
Napper committed his last known crime in November 1993 when he murdered and raped Samantha Bisset, 27, stabbing her up to 20 times.
After killing her, he went to 4-year-old Jazmine's room. She was found smothered in her bed, surrounded by toys, having been sexually assaulted.
The injuries to the Bissets were so horrific a police photographer could not work for months afterwards.
Napper pleaded guilty to manslaughter on the grounds of diminished responsibility in October 1995, on the grounds that he suffered from paranoid schizophrenia and Asperger's syndrome. He was sent to Broadmoor mental hospital. On his arrival, his psychiatrist noted that he was delusional. Napper thought he was a millionaire who had won a Nobel Peace Prize.
- INDEPENDENT
