Information is emerging about the lives of brothers Dzhokhar and Tamerlan Tsarnaev, who are suspected of bombing the Boston Marathon.
Tamerlan, 26, died in a shootout with police on Thursday night. His 19-year-old younger brother, Dzhokhar, was captured late on Friday in Boston.
The brothers lived in the Massachusetts town of Cambridge, home of the prestigious Harvard University. They are thought to have been in the US since about 2001.
There has been mixed information about the route they took to get there. The Tsarnaevs are ethnic Chechens from the troubled Caucasus region of southern Russia. Chechnya is a predominantly Muslim area that has fought for full independence from Russia in the past.
"Dzhokhar" (pronounced Jo-kar) is a popular Chechen name and, on his page on the Russian social networking site VKontakte, the younger of the two brothers is a member of Chechen groups.
The page also reveals that he attended school in the neighbouring Russian republic of Dagestan. The family only lived there for a couple of years after arriving as refugees from Central Asia in the late 1990s.
That's where Dzhokhar was born, but his elder brother, Tamerlan, appears to have lived in Chechnya in the early 1990s. The family fled from there at the height of the first Chechen War.
Information is slowly being pieced together about their lives in the US. The family went to the United States in 2001, though their father has now returned to Dagestan.
'Extremist material'
Anzor Tsarnaev told the BBC that his younger son Dzhokhar was hoping to be a brain surgeon and that he believed the secret services had framed his sons.
"My children never had guns, they never saw them, maybe only on TV," he said.
We know that Dzhokhar attended the Cambridge Rindge and Latin School, becoming an all-star wrestler, and that in 2011 he received a scholarship awarded to promising local high school seniors wanting to pursue further education.
He went on to study at the University of Massachusetts.
His Facebook page gives "Islam" as his world view and says his life goals are "career and money".
Recent entries on what is reported to be his Twitter feed - @J-tsar - include "I'm a stress free kind of guy" on 17 April and "There are people that know the truth but stay silent & there are people that speak the truth but we don't hear them cuz they're the minority", on 16 April. There is nothing to suggest his involvement in Monday's atrocity.
The FBI said its agents had interviewed Tamerlan Tsarnaev in 2001 at the request of a foreign government, but found no cause for concern.
According to a photo slideshow from 2010, he was an amateur boxer who had taken a semester off from the Bunker Hill Community College in Boston to train for a big competition.
In the accompanying captions, he tells the photographer that he is hoping to win enough fights to be selected for the US Olympic team and be a naturalised American. Tamerlan also says that unless Chechnya becomes independent, he would rather compete for the United States than for Russia.
He is quoted as saying: "I don't have a single American friend. I don't understand them."
The well-built boxer is photographed with his young "half Portuguese, half Italian" girlfriend whom he claims has "converted to Islam". He says that he is "very religious".
He also told the photographer that he did not drink or smoke any more - "God said no alcohol" - and expressed concern that there were "no values anymore".
Russian news agency RIA Novosti says "extremist material" was on the YouTube account belonging to Tamerlan Tsarnaev.
The BBC has been unable to confirm the information about material on the page.
"Several albums were posted, one of them titled 'Terrorist'. The album contains two video clips, which are inaccessible, because the account linked to them has been removed. Also on the playlist there are conversations about the religion of Fayz Mohammad, who is famous for his radical utterances," RIA Novosti said.
A video can be found on his page of the Chechen folk singer Timur Mutsurayev, some of whose songs have been put on a list of extremist material by the Russian justice ministry, the news agency reports.
No apparent sign
Meanwhile the brothers' uncle, Ruslan Tsarni, called the attacks an "atrocity", saying the brothers had "put shame on our family and on the entire Chechen ethnicity".
"We are devastated, we are shocked", he told reporters.
"I have been following this from day one but never ever would imagine that somehow the children of my brother would be associated with that. This family does not know how to share their grief with the real victims."
Mr Tsarni said he had last seen his nephews in December 2005.
There had never been any apparent sign of "hatred toward the US" or else he would have turned them over to the police himself, he added.
Asked what he thought provoked the bombings, the uncle said: "Being losers, hatred to those who were able to settle themselves.
"These are the only reasons I can imagine of. Anything else, anything else to do with religion, with Islam, it's a fraud, it's a fake."
