Dramatic and tragic events continue to unfold in Boston last night and today. The FBI identified the two suspected Boston marathon bombers after they robbed a Seven Eleven store in Watertown, a Boston suburb. That led to a deadly gun battle, which left one of the suspects dead. The city is locked down and an enormous manhunt is underway for the second. Who are Dzhokhar and Tamerlan Tsarnaev, the two brothers believed to be Suspect 1 and Suspect 2? Does their Chechen background help explain their actions?