(CNN) – House Homeland Security Chairman Michael McCaul said Sunday he believes Tamerlan Tsarnaev, one of the two Boston Marathon bombing suspects, received training during an extended trip to the Chechen region of Russia in 2012.
McCaul also questioned why the FBI did not take further action against Tsarnaev when he was investigated before his trip.
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“I personally believe this man received training when he was over there and he radicalized from 2010 to the present,” he said on CNN’s “State of the Union.”
In 2011 the FBI interviewed Tsarnaev at the request of Russian authorities, according to a senior U.S. official. Tamerlan Tsarnaev died this week after a late-night shoot-out with police. His younger brother, the other suspect, is in federal custody.
McCaul and fellow Republican Rep. Peter King, the former House committee chairman, prepared a letter to FBI Director Robert Mueller and Attorney General Eric Holder, seeking details about their questioning, a GOP congressional source said Saturday.
Following his interview with the FBI, Tsarnaev traveled to Russia for six months and returned in July 2012. The Tsarnaev family originally hails from the Russian republic of Chechnya and fled the brutal wars there in the 1990s. Tsarnaev's father currently resides in Dagestan.
After Tsarnaev came back, he created a YouTube channel with links to a number of videos–two of which were tagged under a category labeled "Terrorists" and were deleted. It's not clear when or by whom.
“If he was on the radar and they let him go–he's on the Russians' radar–why wasn't a flag put on him, some sort of customs flag? I've done this before. You put a customs flag up on the individual coming in and out. And I’d like to know what intelligence of Russia has on him as well. I would suspect that they may have monitored him when he was in Russia,” McCaul told CNN's chief political correspondent Candy Crowley.
Analysis of his social media accounts and interviews with his family members suggest Tsarnaev became increasingly radical in the last three or four years. But so far, there is no evidence of active association with international jihadist groups.
His uncle, Ruslan Tsarni, who lives in Maryland, told CNN Saturday that he believed Tsarnaev’s radicalization began in 2009 by a friend and recent convert to Islam in the Boston area who Tsnarni says "brainwashed” Tsarnaev.
“I’d suggest this is when it started. This started, all I hear, when I heard on news yesterday it says its radicalization started 2010. No it’s not 2010. It started 2009. And it started right there in Cambridge… The seed was planted there. He didn’t bring it from Dagestan. Using Chechnya is irrelevant at all because they have nothing to do with Chechnya.”
A group of North Caucasus rebels in Dagestan have denied any link to the Boston bombing, according to a statement on a website used by the rebels who call themselves 'Mujahideen of the Caucasus Emirate Province of Dagestan.'
McCaul also argued Tsarnaev was already being radicalized before he went to Russia but maintained his ties to Chechnya could be a strong factor. He said Chechen rebels have had links with Al Qaeda in the past and are considered "some of the fiercest jihadist warriors out there."
The types of explosives that Tsarnaev and his brother are believed to have used last week were similar to weapons used by Al Qaeda, McCaul said.
“I think the larger question right now–If I’m a U.S. attorney is how is - is there more to this cell? Is it just these two or should I cast a wider net to see if anyone else is out there that may be tied to the cell in the United States?”
- CNN's Dana Bash, Elise Labott, and Gregory Wallace contributed to this report.
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