MI5 soon discovered that the two main instigators of the successful attack, Mohammad Sidique Khan and Shehzad Tanweer, had crossed their path before, particularly on the fringes of Operation Crevice.
ECONOMIST: Waiting for al-Qaeda's next bomb
2.
For that matter, why were Tanweer and Mohammed Sidique Khan -- another July 7 bomber -- caught smiling on camera during a whitewater rafting trip a month before their deadly deed?
CNN: A new plague
3.
When British intelligence broke up a plot in 2004 to use fertilizer in a series of attacks, it discounted the plotters' links to two men - Mohammed Sidique Khan and Shehzad Tanweer.
CNN: France asks: Were warnings missed on Toulouse killer?