Soon after 9/11, an FBI informant made an alarming claim: Osama bin Laden's deputy, Ayman al-Zawahiri, had visited the town of Lodi, Calif. in the late 1990s and attended a mosque there. Moreover, two Pakistani imams preaching at the mosque came from a conservative Islamic school, or madrassa, linked to the former Taliban regime in Afghanistan. According to McGregor Scott, the U.S. attorney who le...