Notes presented to the pathologist examining Jean Charles de Menezes, five days after he died, wrongly indicated the electrician was fleeing police shortly before he was shot.
The apparently misleading account could be highly damaging for Scotland Yard if, as claimed, it is proven to have been written by the Metropolitan Police. It would provide evidence the police continued to portray Mr de Menezes in a negative light and provided false information days after his innocence had been established.
The material, contained in leaked documents from the Independent Police Complaints Commission, could provide ammunition for the family and lawyers of the dead man who have accused the Met of an attempted cover-up over the botched operation.
The new material, obtained by ITV News, is contained in the post-mortem details of Mr de Menezes dated on 27 July. The note states the suspected bomber was followed by police into Stockwell Tube station in south London and "he vaulted over the ticket barrier, ran down the stairs on the Tube station".
This account has been directly contradicted by witness statements from police surveillance officers and CCTV footage that suggests the 27-year-old picked up a newspaper at Stockwell Tube station before calmly walking down the escalator.
It was also disclosed that the dead man only had a piece of paper, a watch, a key, and £1.20 in change when he was shot dead.
Meanwhile the head of the authority that oversees the Metropolitan Police said that a public inquiry into Scotland Yard's "shoot-to-kill" policy looks increasingly likely.
Len Duvall, chairman of the Metropolitan Police Authority, also said Scotland Yard was carrying out its own investigation into the policy in the aftermath of the shooting.
His comments come as Mr de Menezes's cousin, Alessandro Pereira, called for the resignation of Sir Ian Blair, the Met's Commissioner, and the prosecution of those responsible.
Brazilian investigators are to fly to London next week for talks with the IPCC to clarify conflicting reports of how he died.
There has been growing unrest about the "shoot-to -kill" strategy contained in the Met's Kratos policy - whereby suspected suicide attackers are shot in the head to prevent them from detonating any explosives.
Mr Duvall, whose authority oversees the running and budget of the Met, said yesterday that there was a growing consensus among "opinion formers and politicians" that some form of public inquiry should be held into the shoot-to-kill policy. "The Met are also beginning to say, maybe it's time to do that," he said.
"I accept there is growing pressure for an inquiry. I have no objection to further scrutiny of the policy. If greater oversight of operations provides public reassurance then that can only be a good thing.
"The MPA will be looking at these issues and the Met are carrying out their own review. Ultimately, however, it is up to the Government to set up a public inquiry."
He added: "But I urge caution if people think there is some kind of magical solution or alternative. The issue of suicide bombers is not going away and there needs to be an effective way of dealing with this threat."
There also remains confusion about what instructions the firearms team that carried out the shooting received from their superiors.Reuse content