Dzhokhar Tsarnaev — the Boston Marathon bombing suspect taken into custody Friday after a massive city-wide manhunt — became curious about his Chechen roots two years ago while a high school student in his senior year.

Brian Williams, a renowned Chechen expert at the University of Massachusetts in Dartmouth, was contacted by Dzhokhar in May of 2011 when the teen had questions about his Chechen roots and the origins of war with Russia for a school report he was writing.

"My theory is that he was sort of vicariously trying to reconstruct his roots to this traumatized homeland," said the Islamic history professor, who is the leading expert on Ibn Khattab, a Saudi known as the "lion of Chechnya."

Police officers and FBI agents spent Friday combing the city for the 19-year-old before surrounding him in the evening. Officers apprehended him after he hid in a boat stored behind a house in a residential area. Dzhokhar has been referred to as suspect No. 2 in Monday's deadly bombing at the finishing line of the famous athletic event.

His older brother, Tamerlan, who is considered the top suspect, died earlier Friday after a shootout with police.

Details about the brothers' ethnic Chechen past surfaced as media outlets around the globe spoke to family members, including an aunt who lives in the Toronto area.

Friends, neighbours and acquaintances of the younger brother described him in media reports almost uniformly as a "sweet," "wonderful" and "lovely" young man who felt grateful to be in the United States and away from his conflict-torn homeland.

Reconstructing links to Chechnya

Williams came into contact with Dzhokhar through a friend who was teaching the teen at Cambridge Rindge and Latin School at the time. The professor said Dzhokhar seemed " to be rediscovering himself and his past and the traumatic wars in Chechnya."

Chechnya is a restive province in Russia's North Caucasus where conflict began in 1994 as a separatist war but later turned into an Islamic insurgency.

"The capital of Chechnya looks like Hiroshima," said Williams, who notes one-fifth of the Chechen population has been killed since 1994. "It got obliterated by the Russians. And one-third of the nation became refugees, including this guy."

"The sheer fact that there's so much terror in their country — suicide bombings and catastrophe — you know it's seems to be too obvious that somehow [it was] the precursor and origins of this act," said Williams, though he noted the attack may not have anything to do with the family's Chechen background.

Around the same time as Dzhokhar was exploring his ethnic history in a school essay, the older brother became more interested in his Muslim faith and began praying five times a day in Islamic tradition, his Toronto-based aunt, Maret Tsarnaev, told CBC News. She insists her nephews could not have been involved in the bombings of the marathon.

Aberfoyle International Security director Andrew McGregor told CBC News that Tamerlan had also recently become interested in apocalyptic Islamic prophecy.

"My theory is that they sort of reconstructed their links to Chechnya," said Williams. "They re-identified with the old homeland. That happens a lot with migrants from other places who take on a sort of diasporic passion for the problems of their former homeland."

Family fled in 1990s

The suspects' father, Anzor Tsarnaev, said Tamerlan was born in the Russian republic of Chechnya and Dzhokhar in the Central Asian nation of Kyrgyzstan after the family fled Chechnya in the 1990s, according to a BBC report.

Their aunt, Maret Tsarnaeva, told CBC News the parents and their youngest son moved to the U.S. in 2002, the family was granted refugee status a few months later and then Tamerlan and his two sisters joined the family the following year.

Dzhokhar, reportedly a second-year medical student at the University of Massachusetts in Dartmouth, has been portrayed as a sociable student while his brother was quoted as saying he didn't have a "single American friend."

Leonid Trofimov, a Queen's University Russian history expert, noted that the Tsarnaev family would have moved from the very traditional, clan-driven society to the more open American culture.

"These are patriarchal families where the males usually make key decisions about livelihood and about how to run the household and all that. It's patriarchal and very much centred around strong families and also on clans," said Trofimov, who is currently in the Boston area teaching at Bentley University. "Loyalty is important, kinship is important."

'Try to brainwash' frustrated Chechens

Canadian-Chechen Adlan Taramov, who studied the radicalization of the Chechen diaspora during his recent master's degree at the University of Toronto, said he can understand how extremists prey on members of the community.

"They try to brainwash people who feel isolated, that feel frustrated since they live in a different country and different environment," said Taramov. "They try to use that frustration of those young people in order to direct them … against their own society."

About 300 Chechens live in Canada, most of them in Toronto, says Taramov.

Most Chechens and refugees seeking asylum in North America, however, feel deeply connected to their new homeland, says Taramov, where they've been given a "chance to live a different life."

In the tightly-knit Toronto Chechen community, he says he hasn't noticed "any signs of extremists or extremism."

"What we see in the community is the opposite actually," said Taramov. "They're really thankful to Canada and to the Canadian society that accepted them and helped them."

As questions continue to abound about the motivation behind the deadly Boston Marathon attack, Taramov echoed a sentiment likely in many people's thoughts.

"Nobody knows what was going on in his mind," said Taramov.