On Wednesday, the FBI arrested 34-year-old Farooque Ahmed on charges that he was plotting to bomb a number of different stops along Washington’s metro rail system. The arrest was made after the government was able to infiltrate his plans and gain Ahmed’s confidence. So how do authorities spot potential terrorists and gain their trust? How difficult is to know when to make the arrest? And just how big of a problem is the threat of terrorists rising from within the U.S.? We ask retired FBI Special Agent Bob Hamer, a veteran of the Joint Terrorism Task Force.
