Why did Shahzad become radicalized?

Many details surrounding Shahzad’s alleged attempt to bomb Times Square are hard to reconcile. Why would someone who spent a decade pursuing U.S. citizenship seek to bomb an American landmark and flee the country within a year of being naturalized? How could someone with a degree in computers, who authorities say admitted receiving bomb-making training in Pakistan, assemble such an unsophisticated and unsuccessful device?…

U.S. officials said the initial phase of their investigation is focused on whether Shahzad was trained by a specific group in Pakistan — including the Pakistani Taliban, which has claimed credit for the attempted attack — and whether he is aware of other plots.

The probe may turn to less pressing questions, including why Shahzad uprooted his family suddenly and returned to Pakistan.