Will the Met learn from its 'annus horribilis'?

Scotland Yard ends a year of controversy with a grovelling apology to the man they tried to entrap for Rachel Nickell's murder

It has been a grim year for the Metropolitan Police, which is still reeling from the premature loss of its commissioner, Sir Ian Blair. It has been riven by race discrimination rows, embroiled in continuing controversy over the shooting of Jean Charles de Menezes, and swamped by a sweeping tide of knife crime. And last week its annus horribilis was compounded when it was compelled to issue a grovelling apology to the man it attempted to entrap for one of the UK's most notorious murders.

Assistant commissioner John Yates's broadcast statement to Colin Stagg had been a long time coming. Mr Stagg spent 13 months in custody after being accused of the 1992 murder of Rachel Nickell, a 23-year-old woman, stabbed to death on Wimbledon Common, south London. She had been murdered in front of her two-year-old son Alex, who was found clinging to his mother's lifeless body.

The case became an even greater cause célèbre when the charges against Stagg were thrown out of court by judge Sir Harry Ognall, who ruled police evidence inadmissible and condemned an attempt by an undercover police woman to catch Stagg in a so-called "honey-trap". What appalled the judge was the detective's pose as a female sexual deviant who would fulfil Stagg's sexual fantasies if he would only confess to the murder of Ms Nickell. He did not.

Critics point out that the detective, whose identity was never revealed, subsequently received £150,000 compensation for the "trauma" of regurgitating these lies, while the real victims, Ms Nickell's partner and son, received considerably less.

Stagg also received compensation, but no apology, until another man admitted the crime and was convicted last week. Robert Napper, a paranoid schizophrenic with a history of rape and murder, admitted killing Ms Nickell. It is known that police made mistakes that should have seen Napper in jail long before he killed Ms Nickell and possibly several others.

Ms Nickell and two further victims of Napper – Samantha Bissett and her four-year-old daughter Jazmine, for whose murders in Plumstead, south London, in 1993 Napper had previously been convicted – might still be alive today had it not been for a series of catastrophic failings by police. In October 1989, Pauline Lasham, Napper's mother, called police to say her son had confessed to a rape on Plumstead Common. Officers failed to link her call to a rape near the common and never even spoke to Napper about the attack or took a blood sample. He was also interviewed over a succession of rapes just weeks after the murder of Ms Nickell but again failed to provide a blood sample which could have put him behind bars before he went on to murder Ms Bissett and her daughter.

Detectives will interview Napper this week about his possible involvement in a series of other violent crimes, including the murders of Claire Tiltman, Penny Bell and Jean Bradley. All died in similar frenzied knife attacks. Ms Tiltman, 16, died in January 1993 after being stabbed 40 times in an alleyway in Greenhithe, Kent; Ms Bell, 43, suffered 50 stab wounds when she was attacked in her car in Greenford, west London, in June 1991; and Ms Bradley, 47, was knifed more than 30 times as she got into her car in Acton, west London. Napper is also suspected of being involved in dozens of sex crimes.

With some understatement, Mr Yates admitted last week: "More could, and should, have been done." Despite this, Scotland Yard said it had "no plans for a further review" of its handling of the investigation. "Homicide investigations have changed significantly since 1992 and we've learnt from these reviews," a spokesman said.

Senior police sources were at pains to stress that an entrapment operation such as the one used against Colin Stagg would never be permitted today. Its architect came in for heavy criticism yesterday from one of Britain's leading forensic psychologists. Professor David Canter of the University of Liverpool said that the investigation had been doomed to failure from the moment that Paul Britton, the psychologist and self-styled criminal profiler behind the attempts to entrap Stagg, was taken seriously by police officers.

Mr Britton had "no basis" for what he was doing, and police officers gave him credibility that anybody who knew what was going on would have challenged, Professor Cantor said. Paul Britton was unavailable for comment yesterday.