Source:
The GuardianThe security services were unable to identify the ringleader of a terrorist gang before it struck London on 7 July 2005, despite having his picture and having seen him associating with other terrorist suspects, the inquest into the 52 deaths heard today.
Mohammad Sidique Khan was spotted by MI5 on the periphery of another terror plot as early as 2003, and was seen with suspected terrorists. Khan was groomed through contact with other suspected terrorists progressing from "an associate of terrorists to prime conspirator and murderer", said Hugo Keith QC, counsel to the inquests, in a statement assessing whether the attacks could have been prevented.
Security services did not believe Khan was a high priority and did not connect different pieces of information relating to him, including training at terrorist camps and having an interest in "martyrdom operations". Various sources pointed towards an individual in the West Yorkshire area, but the authorities never uncovered Khan's full name until he led the biggest mass murder on UK soil.
Read more:
http://www.guardian.co.uk/uk/2011/feb/02/mohammad-sidique-khan-july-7-inquest