This is an interesting story. In the end, a combination of technology and hard cash lead to KSM’s arrest. Note the part of the story that indicates that KSM used as many as 10 cell phones to communicate. The story….

The electronic surveillance network Echelon played a key role in the capture of the alleged September 11 mastermind, Khalid Sheikh Mohammed, it was reported yesterday – as did a $27m (£18m) payment to an “al-Qaida foot soldier”, who may be planning to relocate to Britain. Full Story