Shehzad Tanweer, 22, lived most of his life in Beeston
A friend of the family of one of the London bombers says he believes there are people in Leeds who could help the intelligence services.
Irshad Hussain, a friend of Shehzad Tanweer's family, said he did not believe the bombers acted alone.
But he said it was still a "complete mystery" to Tanweer's parents as to how and why he got involved in the plot.
Mr Hussain, who also knew Mohammad Sidique Khan, lives in Beeston, where three of the bombers had connections.
He said: "I personally don't think they were capable of carrying this out on their own. Not with what we know about them.
"I think there was a mastermind of some kind behind this and someone, somewhere, knows something.
"I don't think those close to the families knew anything. It is still a complete mystery to Shehzad Tanweer's family. But someone knows something and people are very reluctant to come forward to the police."
Mr Hussain added: "It may be a small piece of information like 'I saw Sidique Khan with so and so, or going to so and so' but I think people should come forward.
"But people are very, very suspicious of the police.
"If the community, the police and British intelligence work together I think we can come up with answers."
Mr Hussain was speaking outside the Hardy Street mosque in Beeston Hill, where some of the bombers are known to have worshipped, and just a few hundred yards from Tanweer's family home.
He said: "They (Tanweer's family) loved their kids and its been very difficult for them to come to terms with what's happened.
"Nobody wants to lose their son like that and they've still got no answers. For all the people involved it's a mystery."
The streets of Beeston Hill were almost deserted on Thursday, despite bright sunshine, and residents were even more reluctant to discuss the bombings than they were when the Leeds connection was first established 10 months ago.
One man said: "Everyone just wants to move on."
Arshad Chaudhry, spokesman for Leeds Muslim Forum, said the community felt it had been "under siege" from the media since the July bombings.
He said: "It has been difficult on the community generally, which has been exacerbated by the media hype. People feel they have been under siege and unjustifiably pointed the finger at.
He added: "There have been sporadic attacks on corner shops, and people being sworn at - it was expected and people understand that this kind of backlash was bound to happen. The BNP are very strong in this area."
Mr Chaudhry said the Muslim community did not feel reports by the government into the attacks were of "any use to anyone" and supported calls for an independent inquiry.
Following the publication of government reports into the July 7 bombings, Labour MP for Dewsbury, Shahid Malik, said no security service in the world could guarantee 100% security.
Mr Malik said: "The threat will continue, I think what we need to do is remain alert but not overly alarmed.
"That is the key to being vigilant and to ensure that the relationship between the communities, police, security services and the government is further developed and enhanced."