Tamerlan Tsarnaev was the fifth man since the Sept. 11, 2001, attacks to be suspected of committing terrorism while under investigation by the FBI. http://www.nytimes.com/2013/04/22/us/boston-marathon-bombing-suspects-hoped-to-attack-again.html?ref=us Agents had questioned him a year before he traveled to Chechnya and Dagestan, predominantly Muslim republics in the North Caucasus region of Russia.  The bureau sent two counterterrorism agents from […]