It may be weeks before all the details of Tamerlan Tsarnaev's 2012 travels and the Boston Marathon bombing plot are completely unraveled, according to The New York Times
Authorities in the United States and Russia are working closely to track his path and connections overseas in the months leading up to the April 15 terrorist attack.
Last year, Tsarnaev, 26, traveled to Dagestan for a six-month visit. While there, he sought to join rebel Muslims and was in contact with rebels killed by Russian authorities last spring, Novaya Gazeta, a Russian investigative newspaper, reported.
Tsarnaev left Dagestan in July 2012, two days after Russian police killed several militants, including Russian-born Canadian William Plotnikov. Investigators are trying to determine if Tsarnaev and Plotnikov ever met.
Tsarnaev and his younger brother, Dzhokhar, 19, are accused of leaving shrapnel-filled pressure-cooker bombs at the Boston Marathon's finish line. The older Tamerlan was killed in a shootout in the early morning hours of April 19, and Dzhokhar was captured that night, following a dramatic manhunt that locked down much of the Boston metropolitan area.
Long before the Boston bombing, Tamerlan Tsarnaev's extremist views caught the attention of Russian officials, and in 2011, Russia sent the FBI and the CIA a warning saying it thought Tsarnaev was coming to Dagestan to connect with militant groups.
On Sunday, Republican Rep. Mike Rogers, chairman of the House Intelligence Committee, told ABC News' “This Week” that the “big unknown” with the brothers and their possible radicalization remains what happened when Tamerlan Tsarnaev was in Russia, the Times reported.
Because of his Russian ties, the investigation has expanded to focus on other possible associates and family members of the bombing suspects, including their mother and Tamerlan's American-born wife. Although U.S. officials still believe that the Tsarnaevs mostly were self-radicalized, they also question whether they had help building the bombs and deciding when and where to use them.
House Homeland Security Chairman Michael McCaul told “Fox News Sunday” that the “level of sophistication” of the homemade bombs “leads me to believe there was a trainer.”
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