Dzhokhar Tsarnaev was captured hiding in a tarp-covered boat in a suburban Boston backyard on Friday.
In Washington, Senate Intelligence Committee member Richard Burr, R-N.C., said after his panel was briefed by federal law enforcement officials that there is "no question" that Tamerlan Tsarnaev was "the dominant force" behind the attacks and that the brothers had apparently been radicalized by material on the Internet rather than by contact with militant groups overseas.
The brothers' parents are from Dagestan, a predominantly Muslim province in Russia's Caucasus, where Islamic militants have waged an insurgency against Russia. A U.S. Embassy official said Wednesday that a team of U.S. investigators has traveled to Dagestan to speak to the parents. The official spoke on condition of anonymity because he was not authorized to speak to the media.
Family members reached in the U.S. and abroad by The Associated Press said Tamerlan was influenced by Misha.
After befriending Misha, Tamerlan gave up boxing, stopped studying music and began opposing the wars in Afghanistan and Iraq, according to family members, who said he turned to websites and literature claiming that the CIA was behind 9/11.
"You could always hear his younger brother and sisters say, 'Tamerlan said this,' and 'Tamerlan said that.' Dzhokhar loved him. He would do whatever Tamerlan would say," recalled Elmirza Khozhugov, the ex-husband of Tamerlan's sister. He spoke by telephone from his home in Almaty, Kazakhstan.
The brothers, who came to the U.S. from Russia a decade ago, were raised in a home that followed Sunni Islam, the religion's largest sect, but were not regulars at the mosque and rarely discussed religion, Khozhugov said.
Then, in 2008 or 2009, Tamerlan met Misha, a heavyset bald man with a reddish beard. Khozhugov didn't know where they met but believed they attended a Boston-area mosque together.