The discrepancies in the testimony of the Tube passengers and the police, who insisted they had identified themselves, were revealed yesterday in a long-awaited report from the Independent Police Complaints Commission (IPCC).
The watchdog's findings set out the confusion, miscommunication and panic which led to the death of the 27-year-old Brazilian, who was mistaken for a suicide bomber and shot seven times in the head.
It emerged that the differences in accounts from police and civilian witnesses led to some 15 officers being interviewed under caution for murder, manslaughter, gross negligence and misconduct in public office. No charges were brought.
The report also stated that while police were allowed to return to base, refresh and confer, civilians were expected to make statements in the immediate aftermath of the trauma at Stockwell station without being allowed to speak to each other.
However, the report stated, all the passengers were clear on one point: "It is perhaps significant that none of the 17 witnesses recall hearing the police officers shout 'police' or 'armed police' immediately prior to the shooting, whilst the eight police officers on the train recall either shouting or hearing this.
"Those officers have been interviewed under caution concerning allegations they conspired to pervert the course of justice."
Police are required to identify themselves when not acting under "shoot to kill" - known as Operation Kratos - status.
Mr de Menezes, an electrician, was under surveillance on 22 July, 2005 - a day after a failed bomb attack on London. He was mistaken for Hussain Osman, a suspected suicide bomber, as he lived in the same block of flats but was never identified beyond doubt by the surveillance team.
The report stated: "None of the surveillance team positively identified the subject. Furthermore, none of them agree they heard anyone communicate it was a positive identification."
The report also concluded that several opportunities to stop Mr de Menezes on the way to the Tube station were missed.
Armed response officers from the Met's CO19 unit were not in place to stop the suspect leaving the flats, and were later found to be in the wrong place to intercept him.
Commander Cressida Dick, who led the operation from Scotland Yard, had also been 25 minutes late for a crucial briefing on the case, the report found.
Control Room 1600, where Ms Dick was based, was noisy and chaotic on the day, and although no officer positively identified the suspect, Scotland Yard became convinced they were tailing a terrorist, the IPCC learned.
Ms Dick had told officers: "The male must not be allowed to get on a train at all costs," but had not given the order to shoot to kill.
The IPCC said Ms Dick should have stressed Operation Kratos status had not been engaged, and there was confusion over what the order to "stop" Mr de Menezes meant. Charges of gross negligence against Ms Dick were been considered and ruled out.
The 167-page report also detailed the final moments of Mr de Menezes' life on board the Northern Line train.
Witnesses said he had not acted suspiciously, vaulted a ticket barrier and was not wearing bulky winter clothing, contrasting police claims in the hours after his death. When police stormed the carriage, Mr de Menezes stood up - like his fellow passengers - only to be grabbed by a surveillance officer and pushed back on to the seat.
One female witness recalled seeing a man sitting two seats away with a gun to his neck. She "was not able to identify any of the men as police officers neither did she hear the word 'police' shouted".
One of the officers, identified as "Charlie 2", said he was convinced Mr de Menezes was about to detonate a bomb. He held his gun to Mr de Menezes' head and fired. Another officer, Charlie 12, also fired his weapon.
Witness accounts described how Mr de Menezes was attempting to get off the train through the open doors as the armed officers ran on board.
The report stated: "He [Mr de Menezes] had been in London on 7 and 21 July, 2005, and, in common with all commuters, he too was probably in fear of further bombing campaigns.
"His actions were more likely attempts to leave the train to avoid any further incident."