The FBI did not name the foreign government, but the two officials said it was Russia. The officials spoke on condition of anonymity because they were not authorized to talk about the matter publicly.
The FBI said that in response, it interviewed Tamerlan Tsarnaev and relatives, and did not find any domestic or foreign terrorism activity. The bureau said it looked into such things as his telephone and online activity, his travels and his associations with others.
An uncle of the Tsarnaev brothers said he had a falling-out with Tamerlan over the man's increased commitment to Islam.
Ruslan Tsarni of Montgomery Village, Md., said Tamerlan told him in a 2009 phone conversation that he had chosen "God's business" over work or school. Tsarni said he then contacted a family friend who told him Tsarnaev had been influenced by a recent convert to Islam.
Tsarni said his relationship with his nephew basically ended after that call.
As for Dzhokhar Tsarnaev, "he's been absolutely wasted by his older brother. I mean, he used him. He used him for whatever he's done," Tsarni said.
Albrecht Ammon, a downstairs-apartment neighbor of Tamerlan Tsarnaev in Cambridge, said in an interview that the older brother had strong political views about the U.S. Ammon quoted Tsarnaev as saying that the U.S. uses the Bible as "an excuse for invading other countries."
Tamerlan Tsarnaev studied accounting as a part-time student at Bunker Hill Community College in Boston for three semesters from 2006 to 2008, the school said. He was married with a young daughter. Dzhokhar Tsarnaev was a student at the University of Massachusetts Dartmouth.
As of Saturday, more than 50 victims of the bombing remained hospitalized, three in critical condition.