Tamerlan Tsarnaev, the Boston Marathon bombing suspect killed Friday in a shootout with police, travelled to Russia in 2012 and may have done so under an alias, the chairman of the House Intelligence Committee, Rep. Mike Rogers, said on NBC’s "Meet the Press" Sunday. The six-month trip “becomes extremely important” as a key to the investigation, Rogers said. He added that the visit to Russia is “probably where he got that final radicalization to push him to commit acts of violence and where he may have received training” in terrorist techniques. Rogers, a former FBI agent, said the FBI had questioned Tamerlan Tsarnaev after being given information from a foreign intelligence service “that they were concerned about his possible radicalization.” The agents “did a very thorough job” of investigating him, but when the FBI asked for more help from that foreign intelligence service, it got no further cooperation. But Sen. Lindsey Graham told CNN Sunday Tamerlan Tsarnaev is the kind of person "you don’t want to let out of your sight,” and that it was a mistake for federal authorities to have lost track of him. The Tsarnaev family were ethnic Chechens, an embattled Islamic nationality in Russia.