Bomb Suspect Calm as First Blast Ripped Apart Boston Marathon

Bomb Suspect Calm as First Blast Ripped Apart Boston Marathon

FBI via Getty Images

Investigators are working with Russian authorities as they focus on a six-month trip that 26-year-old Tamerlan Tsarnaev took last year to Chechnya and neighboring Dagestan, both regions of Russia that have been roiled by Islamist separatist movements.