The central witness in the trial of former Scotland Yard commander Ali Dizaei has been told he will not be prosecuted for rape.
Waad al-Baghdadi, 25, was arrested last year by detectives investigating an alleged sexual assault at a home in Westminster.
He was questioned on suspicion of rape after a woman came forward to police to complain about a “historic” incident.
But the freelance internet developer was told that he should be released from bail and face no further action.
News of the aborted police investigation came as Dizaei, 48, prepares to challenge his conviction for corruption in the High Court.
His legal team, led by Michael Mansfield QC, believe there is fresh evidence that shows the case against him is fundamentally flawed.
They want judges to examine claims Mr al-Baghdadi used a false name and nationality when he appeared in court under oath.
Dizaei was jailed for four years in February last year after a jury found he attacked Mr al-Baghdadi outside a Kensington restaurant in a row over money.
Details of the bid are expected to be laid bare during a three-day hearing at the Court of Appeal in late March. No date has been set.
A Metropolitan Police spokesman said: “The Met has this afternoon been informed by the Crown Prosecution Service (CPS) that they have decided a 25-year-old man who was on bail, after being arrested on September 28, 2010, in connection with an allegation of a sexual offence, should be released from bail with no further action.”