Friday's shooting: The key questions

Why did the police follow a man who had nothing to do with the bombings?

Documents from one of the unexploded rucksack bombs provided the address of a purpose-built block of flats in Tulse Hill, south London. A police surveillance team staked out the property, but appears to have been confused by the fact it was divided into nine flats. Jean Charles de Menezes, who lived in one of the flats, emerged from the block, in what police described as a heavy-looking jacket. The foreign-looking man was considered a possible terrorist and followed. But he was a relatively light-skinned Brazilian, who may have been wearing a heavy jacket because he felt the cold here, even in summer.

Why was a suspected suicide bomber allowed on to a bus while under the watch of the police?

The surveillance team called in firearms officers to make an arrest, but not before the suspected bomber had walked for about five minutes and taken a three-mile bus ride towards Stockwell Tube station. It could be there was not time for the armed officers to arrest the suspect before he got on the bus and then had to wait until he was on open ground. Alternatively the suspect may have jumped on to a bus and surprised the surveillance officers, or they made a blunder and allowed him to get public transport.

Why did he run from police when ordered to stop?

Being confronted by three armed plainclothed officers, he could have been frightened and fled. Coming from Brazil, he may have been particularly nervous of armed officers. In the Brazilian state of Sao Paulo, police shot dead 1,470 people in 1992. This fell to 272 in 2001, although half were shot in the back. Although his friends and relatives say he was living legally in Britain, it appears he was here on a student visa, and was working illegally as an electrician. He could have been trying to avoid capture. So far the only details of his final moments come from eyewitness accounts, which are often inaccurate. Until CCTV footage is examined and released, we will not know whether he was challenged and if he did - as described - jump over the ticket barrier and run downstairs.