The Metropolitan Police is expected to drop its case against one of Britain's most senior police officers from an ethnic minority after an investigation costing an estimated £3m.
Superintendent Ali Dizaei, head of policing for Kensington and Chelsea, is facing eight counts relating to alleged false expenses claims. His trial is listed to begin next month at the Old Bailey.
However, court papers reveal that a special hearing to have the legal proceedings withdrawn has been arranged for tomorrow.
It is now likely that the Crown Prosecution Service will not contest an application by Supt Dizaei's legal team for the proceedings to be scrapped.
That is expected to cause considerable embarrassment to the Metropolitan Police, which spent months gathering evidence against the superintendent. He has always strongly denied the charges against him.
A total of 42 police officers from Scotland Yard's anti-corruption unit were involved in the investigation, code-named Operation Helios, which involved the bugging of Supt Dizaei's telephone as well as extensive surveillance work.
Supt Dizaei, who was born in Iran, was tipped to become Britain's first chief constable from an ethnic minority however he was suspended from duty more than a year ago amid the fraud allegations, which relate to vehicle mileage claims.
Legally trained, Supt Dizaei passed the coveted senior command course after just 13 years of police service.
The father of three, who is aged in his early forties, was a senior adviser to the national Black Police Association and has been outspoken about the Met's handling of race-relations issues. He once revealed in an interview that he had been stopped and searched.
The Met has been criticised in the past for its attitude towards its officers from minority backgrounds.
In 2001, Chief Inspector Leroy Logan, an MBE and chairman of the Met's Black Police Association, was investigated following allegations that he had fiddled an £80 expenses claim. He denied any wrongdoing and the Met dropped plans to prosecute him after it admitted it had insufficient evidence against him.
Brian Paddick, Britain's most senior openly gay police officer, was transferred from his job as Commander of Lambeth, in south London, by the Met following claims about his lifestyle by a former lover.
Commander Paddick was cleared of any disciplinary charges after an eight-month investigation by the Crown Prosecution Service, the Police Complaints Authority and the Metropolitan Police Authority.
Michael Mansfield QC, the leading human rights barrister, was appointed by Supt Dizaei to act as his defence in the pending trial.
Supt Dizaei has launched employment tribunal proceedings against the Metropolitan Police, alleging race discrimination and victimisation.