the Northwest Frontier Province where Taliban and Al Qaeda bases are woven into the rugged, impenetrable terrain along the border with Afghanistan.

Specifically, Pakistani officials said, Shahzad had visited the tribal areas, where the Pakistani Taliban is deeply entrenched.

Pakistani authorities said the family owned a home in Peshawar, the lawless city that sits at the foot of the Khyber Pass leading into Afghanistan and where the fiery sermons of Taliban-inspired clerics echo from the minarets of local mosques.

"There's a very good possibility that he got his training at a militant camp in the badlands near Nizampur," said one source, referring to a small village set high in the iron mining areas of the North-West Frontier Province.

Shahzad told investigators he acted alone and denied any ties to radical groups inshooting 13 people last year at Fort Hood, Texas. Also, Najibullah Zazi, a Denver-area airport shuttle driver who pleaded guilty in February in a plot to bomb New York subways. And a Pennsylvania woman who authorities say became radicalized online as "Jihad Jane" and plotted to kill a Swedish artist whose work offended Muslims.

Salman Ahmed reports from Karachi for GlobalPost.