US national David Coleman Headley, nabbed by FBI for plotting a major terror attack in India at LeT's behest, was a frequent flyer who made multiple trips to Pakistan where he spent substantial time undergoing training from the terror group, American investigators have said.

Forty-nine-year-old Headley was arrested on October 3 along with Tahawwur Hussain Rana, 48, a Canadian citizen of Pakistani origin, by FBI at Chicago's O'Hare International Airport as he prepared to board a flight to Philadelphia, intending to travel to Pakistan.