As an eighth-grader in a Cambridge public school, suspected Boston Marathon bomber Dzhokhar Tsarnaev was quiet, friendly, spoke good English and seemed at home in his adopted country.
While hundreds of police officers pursued the 19-year-old during a nationally-televised rampage across Boston Friday, a former classmate recounted memories of the refugee who, according to counterterror officials, became a U.S. citizen on an ironic date: Sept. 11, 2012.
The story of the Boston bombers, Dzhokhar Tsarnaev and his 26-year-old brother, Tamerlan, is still unfolding at high speed. Many aspects of the case, including the brothers' motivations, are not yet clear.
But a portrait began to emerge Friday based on ProPublica interviews with counterterror officials, the public statements of relatives and associates, and reports in the media.
Counterterror officials believe the brothers were Islamic extremists. And the information available so far suggests that they appeared to integrate well into U.S. society, yet slid into a spiral of Islamic radicalization with bloody results. The profile has similarities to the home-grown terrorists behind attacks in Madrid in 2004 and London in 2005, according to counterterror officials.
"He was always a nice kid," said Cam Blauchner, who attended middle school with Dzhokhar, in a telephone interview with ProPublica. "He was shy, but not in a creepy way. He was a sweet guy. We played soccer together. I knew he was from Chechnya, but he never talked about it. He never mentioned his religious affiliation. I didn't know he was Muslim."
At some point, however, Dzhokhar and his brother plunged into a subculture that is grimly familiar to counterterror agencies in Europe and, to a lesser but worrisome extent, the United States, officials said.
There are signs that the brothers showed interest in the conflict in Syria, which has drawn al Qaida fighters and other militants from across the Muslim world and Europe, according to a U.S. counterterror official. Like others interviewed for this story, the official requested anonymity because he was not authorized to discuss the ongoing case.
The brothers had viewed videos about the plight of Syrian Muslims, the official said. Syria is the latest hotspot on the world map of jihad. Holy warriors a decade ago were inspired by videos about brutal combat between jihadis and Russian troops in the brothers' family homeland: the predominantly Muslim region of Chechnya, a breeding ground for al Qaida fighters in the late 1990s and early 2000s.
Tamerlan had viewed a video titled "I Dedicate My Life to Jihad," according to a U.S. law enforcement official. The brothers also were apparently influenced by the online Inspire magazine, a slick English-language publication that plays a strong role in disseminating ideological tracts and bomb-making techniques to Western extremists, the U.S. counterterror official said.
"It's like London, it's like Madrid in the radicalization," the counterterror official said. "These guys were produced by the international jihadist machine. The biggest thing is they were individuals willing to die. They were committed. There was interest in events overseas affecting Muslims. And a lot of Internet activity 2014 the things that everyone in the counterterror community worries about."
The brothers had traveled in recent years to Russia, officials said. Tamerlan returned via New York from a trip to Moscow in July 2012, according to a U.S. law enforcement official. But officials said nothing so far indicates recent travel to Chechnya, in southern Russia, or war zones where terrorist groups provide training and direction to Western recruits.