The Independent Police Complaints Commission says the results of its investigation into the death of Jean Charles de Menezes might be sent to the Crown Prosecution Service, the BBC reported.
Menezes, an electrician from Brazil, was gunned down in the Stockwell Tube station by police who thought he might be a suicide bomber. The shooting took place in July, not long after the July 7 Transport bombings.
At the time, officers made a number of claims that proved to be untrue, including that Menezes entered the station without paying the fare.
Nick Hardwick, chairman of the IPCC, said investigators had interviewed every passenger in the station at the time of the shooting as well as the police officers.
"We are confident we know, second by second, what happened on that train," he said.
The IPCC is conducting a second investigation into Metropolitan Police Commissioner Sir Ian Blair's handling of the aftermath.