The critical mistake of sending 1000 dollars home before Eid proved to be the undoing of alleged terror mastermind Yasin Bhatkal, who was arrested on Wednesday night in north Bihar, near the border with Nepal. For six months, intelligence agencies had kept a close watch on the Indian Mujahideen (IM) co-founder's wife and his alleged associates in Delhi, through an informer close to the family. They had also tapped phone calls to the family.