Russian intelligence officials believe Tamerlan Tsarnaev may have met with militants while living in a Russian province in 2012, a U.S. counter-terrorism official told the Los Angeles Times on Thursday.
Tsarnaev, 26, one of the two brothers accused of bombing the Boston Marathon, was living in Cambridge, Mass., at the time of the bombings.
Officials have scoured his background for potential sources of radicalization in the years leading up to the attacks. They have focused on the six months he spent in Dagestan, a region in southern Russia.
Russian authorities had warned the FBI and CIA in 2011 that Tsarnaev might have ties to radical Islamist groups.
“It looks like there was some interaction,” the counter-terrorism official said of the 2012 visit. “It doesn’t seem like it was involving logistics or planning. They certainly weren't working with him because they were focused primarily on the traditional Russian enemy."
The official, who requested anonymity because he was not authorized to speak about the investigation, added, "There is no evidence of pre-operational planning or training or even that this was a source of his radicalization.”
By the time Tamerlan Tsarnaev arrived back in Boston in July 2012, his views on Islam had grown more conservative.
He died after a gun battle with police in Watertown, Mass., on April 19, and his brother, Dzhokhar Tsarnaev, 19, was arrested.
Tamerlan Tsarnaev's body was released from the Office of the Chief Medical Examiner of Massachusetts in Boston on Thursday evening, spokesman Terrel Harris told The Times.
The body was claimed by an undisclosed funeral service on behalf of his family, Harris said, adding that burial information was considered private.
A cause of death will not be formally announced until the funeral service signs and files a death certificate, Harris said.
Tsarnaev's widow, Katherine Russell, had previously said that she wanted her husband's body to be released to his family, who have remained in Russia after backing off earlier promises to visit the U.S.
Zubeidat Tsarnaeva, Tamerlan's mother, said Saturday she was wary of visiting the United States because of law enforcement questions about her possible role in the bombings.
She has previously expressed doubts about her sons' involvement in the attack, which killed three people and left more than 260 others wounded.
Dilanian reported from Washington, D.C., and Pearce from Los Angeles.