A senior police officer, who claims he has been subjected to a "witch hunt" since joining the Metropolitan Police, has been acquitted of dishonesty.
Mr Dizaei was cleared of perverting the course of justice in April
The Crown Prosecution Service (CPS) decided not to proceed on Monday with a second trial against Superintendent Ali Dizaei alleging that he made false expenses claims for mileage.
A jury cleared the Iranian-born officer, from Henley-on-Thames, Oxfordshire, in April of perverting the course of justice and misconduct concerning a report of vandalism to his car.
The Black Police Officers Association (BPA) said it was a "defining moment" for the Metropolitan Police and called for an independent inquiry into the investigation, which has cost millions of pounds.
During the trial it emerged the charges were brought against Mr Dizaei after anti-corruption officers failed to find evidence for more serious offences.
An undercover operation investigated claims that the 41-year-old, who was tipped to become a chief constable, was corrupt, a possible Iranian spy and a drug user.
These suspicions were in contrast to the officer's growing public profile as an outspoken critic of racism in the police.
The court heard he was seen by some to be ambitious, too critical of the police and too close to the Iranian community.
He was also unpopular with a number of officers for flouting uniform rules by wearing designer belts and sunglasses, the jury was told.
The two-year investigation and subsequent legal action at the Old Bailey is estimated to have cost £3m - the most expensive investigation into a single officer.
But eventually Mr Dizaei, a superintendent in the Kensington police division, was charged with making a false report about damage to his BMW car.
'Cost taxpayers money'
Prosecutor Richard Horwell said the car had been damaged near a gym in Kensington where it had been spotted by undercover officers on 6 September 2000.
But when Mr Dizaei reported the damage, he claimed it was in Cope Place, near the police station.
Mr Dizaei said he had first seen the damage when the car was parked in Cope Place, but he drove it near the gym to catch the Tube to a BPA meeting.
He told the jury he lied about where he had left the car because he did not want his boss to know he had attended a BPA meeting.
"It is not something I am proud of," he said.
"I made a mistake. At the time I did not think the incorrect version would hamper the police investigation or cost taxpayers money."
Michael Mansfield QC, defending, said the police investigation was out of proportion and included monitoring "virtually every aspect of his life".
"If one wants to use emotive language, it turns into a witch hunt," he said.
"They had to find something and the something they had to find to justify everything that had happened was some form of criminality."
But outside court, the Metropolitan Police defended their inquiry and said they made no apology for spending the money investigating an officer.
Back in uniform
Deputy Assistant Commissioner Stephen House said: "This was not about scratches on a car and fiddling expenses, but about the integrity and trust of an extremely senior police officer."
Mr Dizaei said he did not blame the force or the CPS but "a number of individuals in those two organisations who have set out on a personal crusade to try to destroy my life and my career".
He still faces 12 internal disciplinary matters and plans to go ahead with a racial discrimination employment tribunal case against the Met.
But he added: "I look forward to getting back into uniform and serving the people of London."
A ban on reporting the proceedings was lifted by the Recorder of London Judge Michael Hyam.