Some luck!
It's amazing that the reason behind the success in finding the terrorists in Spain was because one of the cell phones supposed to detonate the bomb didn't work.
It was set at 07:40 PM instead of 07:40 AM. The police found the unexploded bomb and cell phone (before the 12 hours had elapsed) and found the suspects thanks to the pay card in the cell phone!
Quite a luck!
Raoul