From outsiders to bombing suspects in Boston: 'Aspiring jihadists' or struggling to fit in?
Tsarni also told reporters he hadn't spoken to his nephews in months.
One of the brothers' neighbors, Albrecht Ammon, recalled an encounter in which the older brother argued with him about U.S. foreign policy, the wars in Afghanistan and Iraq, and religion.
Ammon said Tamerlan described the Bible as a "cheap copy" of the Quran, used to justify wars with other countries.
"He had nothing against the American people," Ammon told The Associated Press. "He had something against the American government."
Dzhokhar, on the other hand, was "real cool," Ammon said. "A chill guy."
The cases of homegrown and first-generation terror suspects in the U.S. are few, but the U.S. intelligence community has long been concerned about such potential attackers, particularly the threat posed by people like the Tsarnaev brothers who have no formal terror ties.
"And what makes them especially worrisome is that they're really difficult for us to detect and, therefore, to disrupt," Matt Olsen, director of the National Counterterrorism Center, said in June 2011 about homegrown violent extremists.
The U.S. intelligence director's office has declined to provide official government data on homegrown terrorists, or comment on the Tsarnaev brothers and the investigation into the bombings.
But an August 2011 White House policy paper on countering and preventing violent extremism in the U.S. said that while the numbers remain limited, "violent extremists prey on the disenchantment and alienation that discrimination creates, and they have a vested interest in anti-Muslim sentiment."
Kenneth Wainstein, who served as the White House homeland security adviser and a top Justice Department lawyer under President George W. Bush, said homegrown and newly immigrated militants develop their extreme views over time and are often borne out of sense of isolation. It's a problem that has not been as prevalent in the United States as in Europe, which has a larger number of ethnic and nationalist divisions.
"But I think we have seen, over the last few years, some pretty clear and sobering examples of people inspired by overseas terror groups and terror propaganda," Wainstein said Friday, before Dzhokhar was captured. "They fit more in the category of where you have people who are radicalized here without any apparent connection overseas. A kid can go into his room get radicalized on the Internet without direct connect with anyone overseas, or even without going down the street to the radical preacher. That makes it very hard to detect that person, and poses a significant problem for the intelligence community and law enforcement."
Investigators also are looking at the six months Tamerlan Tsarnaev spent last year in his ancestral homeland in the predominantly Muslim provinces of Dagestan and Chechnya to see whether he was radicalized by the militants in the area who have waged a low-level insurgency against Russian security forces for years.
While there, he regularly attended a mosque and spent time learning to read the Quran, but "did not fit into the Muslim life," according to his aunt, Patimat Suleimanova.
She said he seemed more American than Chechen.
Associated Press writers Pete Yost and Arsen Mollayev, in Makhachkala, Russia, contributed to this report. Follow Lara Jakes on Twitter at https://twitter.com/larajakesAP and Eileen Sullivan at https://twitter.com/esullivanap
- Photo gallery: Remembering Katrina 10 years...
- ACT scores, 2015: A breakdown of each state,...
- The 25 most educated cities in America: Where...
- Poll: Utahns would take Donald Trump over...
- 'North Dakota' not among potential new...
- Video: Bush returns to New Orleans for 10th...
- Calm on Wall Street: A turbulent week ends on...
- As Common Core results trickle in, initial...
- Poll: Utahns would take Donald Trump... 77
- Trump starts new media feud with... 36
- What keeps teachers from staying in the... 34
- GOP presidential candidate Jeb Bush has... 28
- Planned Parenthood alleges 'smear' in... 21
- USC's Steve Sarkisian apologizes for... 17
- Fired reporter kills 2 former... 17
- Trump says he's proud he booted... 16