One of the country's leading criminal profilers faces being struck off after being accused of misconduct by the man cleared eight years ago of murdering Rachel Nickell on Wimbledon Common.
Paul Britton, 56, is due to appear this week before a preliminary disciplinary hearing of the British Psychological Society (BPS), which will examine complaints made by Colin Stagg, 37, that the criminal psychologist acted unprofessionally when advising police on the inquiry.
Mr Britton was criticised by other psychologists for his part in the "honey trap" scheme in which an undercover policewoman wrote to Mr Stagg, encouraging him to swap sadomasochistic fantasies. Mr Britton helped script the letters.
Mr Stagg claims the psychologist ruined his life and did not carry out his duties in a proper and scientific manner. He was cleared of stabbing Ms Nickell, a former model, in front her two-year-old son, at an Old Bailey trial in 1994.
If found guilty of professional misconduct, Mr Britton, who strongly denies any wrongdoing, could be expelled from the British Psychological Society, which would prevent him working in the public sector. Mr Britton has worked on dozens of police cases including that of mass murderer Fred West. the kidnapping of Stephanie Slater and the murder of James Bulger
The murder of Ms Nickell in July 1992 generated huge media interest and police came under strong pressure to find the killer. Their prime suspect was Colin Stagg, but they had little evidence.
They turned to Mr Britton to draw up a profile of the killer. They also asked him to help design a covert operation aimed at testing whether the suspect would eliminate or implicate himself. An undercover policewoman known as Lizzie James – not her real name – began exchanging letters with Mr Stagg as part of Operation Edzell. He did not confess to the murder but detectives believed he had revealed details which could lead to his conviction.
Mr Britton concluded that both the suspect and the killer "had a sexually deviant-based personality disturbance". Mr Stagg was arrested in 1993 and charged with the murder. Mr Britton's report, which concluded that the defendant was one of a very small sub-group who suffered from this particular sexual deviation was produced as evidence, a first for a British court.
When the case reached the Old Bailey the judge, Mr Justice Ognall, threw out Mr Britton's evidence. He described the undercover operation as "wholly reprehensible". He said police had shown "excessive zeal" and had tried to incriminate a suspect by "deceptive conduct of the grossest kind".
The prosecution withdrew its case and Mr Stagg was acquitted. Ms Nickell's killer has not been brought to justice.
The BPS's disciplinary committee will begin a three-day hearing tomorrow to consider whether to order a full inquiry. Mr Britton says he acted with "complete professional and personal integrity".