Senior police sources have confirmed that the officers involved in the operation that led to the shooting of Jean Charles de Menezes, the innocent Brazilian would not have needed to shout a warning before firing.

The killing of de Menezes was a terrible error that has devastated his family and threatens to sap police morale at a critical time in the war on terror. It now threatens to become a cause celebre among human rights activists.

Relatives mourning at de Menezes’s funeral on Friday complained that he had been “exterminated” without any chance to surrender. One sign at his funeral in his home town of Gonzaga read “Jean, martyr of British terrorism”.

Gareth Peirce, one of Britain’s most prominent defence lawyers, is representing the family of de Menezes against the police. The Independent Police Complaints Commission is studying CCTV footage that caught de Menezes’s last moments. What is already clear is that the initial accounts of his death on July 22 were wrong.

When the shooting at Stockwell Underground station was first confirmed, a senior police source told reporters, off the record, that they had killed one of the would-be suicide bombers who was on the run after the failed July 21 bombings. Sir Ian Blair, the Metropolitan police commissioner, said that the shooting was “directly linked” to the terrorist operation.

The man, according to the police, was suspect because of his “clothing and behaviour”. He had been followed from a house that had been under surveillance. When he was challenged at Stockwell, he ignored instructions and ran. He had vaulted over the ticket barrier and was wearing a dark bulky jacket that could disguise a bomb.

One witness had de Menezes as an Asian with a beard and wires coming out of his torso. The truth is more mundane. De Menezes, an electrician, was travelling to north London to fix a fire alarm.

He was not wearing what witnesses called a “black bomber jacket”, but a denim jacket. It was about 17C and his clothing would not have been out of the ordinary.

He did not vault a ticket barrier, as claimed. He used a travelcard to pass through the station in the normal way. His family believes that he may have started to run simply because he heard the train pulling in — something Londoners do every day. Indeed, a train was at the platform when he got there.

Police clearly believed that de Menezes might have been a suicide bomber, even though he was not carrying a rucksack. This raises a key question: why was de Menezes allowed to board a bus in Tulse Hill and travel to Stockwell, if officers thought that his body might be rigged with explosives? It also raises questions about the new shoot-to-kill protocol. The protocol — which is specific to individual targets — can be put into force only when police have reason to believe that a suspect may be carrying a bomb. The order can be issued only by a “gold commander” at Scotland Yard.

The order, once given, clears officers to shoot the suspect in the head if they believe that he is about to activate the bomb. The idea is to give the individual no time to react. Police do not have to shout a warning before they act: to do so would negate the effect of the head shot.

Some witnesses say that de Menezes was given no chance to give himself up. They say that once on the train he was pinned to the ground and shot.

Lee Ruston, 32, was at the bottom of the escalator that de Menezes ran down. He believes that he heard every word said by officers.

According to him, officers did not say the word “police” or offer de Menezes the prospect of arrest. “I heard a voice shouting ‘get on the floor, just get on the floor’. Another voice said the same, ‘get on the floor’. I then heard the crack of gunshots,” he said.

Whether de Menezes was given a warning — as police claimed — will be critical to the inquiry, as will the assessment of the gold commander who decided that de Menezes was a threat and implemented the shoot-to-kill protocol.

De Menezes lived in a block of flats which was under surveillance because of its links to the terror attacks, but what was the evidence that he was a specific risk? It will outrage the family if he was killed because of apparently suspect behaviour and the misfortune to live at an address linked to terrorism.

Blair said that the public should also appreciate the bravery of the officers, who surrounded a suspect they thought might blow himself up.

As one officer said yesterday: “They’ve done a good job for their country. But of course, they are very sad.

“They thought they were acting in the best interests of everybody and on the information they were given. It’s a very sad thing, isn’t it.”

Additional reporting: Michael Smith, Andrew White

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