Dzhokhar Tsarnaev and Tamerlan Tsarnaev, two brothers from a region near Chechnya, are believed to be the perpetrators in the Boston Marathon bombing and a violent crime spree Thursday night and Friday morning that saw an MIT police officer killed.
But who are the two men believed to be behind a week of terror in one of America's largest cities? You can read their stories below.
BOSTON (AP) — Tamerlan Tsarnaev practiced martial arts and boxing, even aspiring to fight on the U.S. Olympic team. Dzhozkar Tsarnaev had been on the wrestling team at a prestigious high school and won a scholarship from the city to pursue higher education. Neighbors recalled the ethnic Chechen brothers, living on a quiet street in Cambridge, Mass., riding bikes and skateboards.
Two brothers, one dead, one alive and at large. After hours of only grainy images of two men in baseball caps to go on, a portrait gradually emerged Friday of the men suspected in the Boston Marathon bombing.
The brothers, who came from a Russian region near Chechnya, lived together on Norfolk Street in Cambridge. They had been in the country for about a decade, according to an uncle, Ruslan Tsarni of Montgomery Village, Md.
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Less was immediately known about Tamerlan, believed to be 26 when he was killed overnight in a shootout. He was the stockier one identified in video released to the public, wearing a black baseball cap and khaki pants. He was involved in martial arts, and competed in boxing matches. According to a crime website he was once arrested for domestic assault on a girlfriend.
"I don't have a single American friend. I don't understand them." he was quoted as saying in a photo package that appeared in a Boston University student magazine in 2010.
He identified himself as a Muslim and said he did not drink or smoke: "God said no alcohol." He said he hoped to fight for the U.S. Olympic team and become a naturalized American. He said he was studying at Bunker Hill Community College to become an engineer.
Dzhokhar, 19, attended the prestigious Cambridge Rindge and Latin school, participating on the wrestling team. In May 2011, his senior year, he was awarded a $2,500 scholarship from the city to pursue higher education, according to a news release at the time. That scholarship was celebrated with a reception at city hall.
He attended the University of Massachusetts at Dartmouth, Mass., university officials said Friday.
The school would not say what he was studying. The father of the suspects, Anzor Tsaraev, told the AP his younger son was "a second-year medical student," though he graduated high school in 2011.
"My son is a true angel ...," he said by telephone from the Russian city of Makhachkala. "He is such an intelligent boy. We expected him to come on holidays here."
Dzhokhar's page on the Russian social networking site Vkontakte says that before moving to the United States, he attended School No. 1 in Makhachkala, the capital of Dagestan, a predominantly Muslim republic in Russia's North Caucasus that has become an epicenter of the Islamic insurgency that spilled over from Chechnya. On the site, he describes himself as speaking Chechen as well as English and Russian. His world view is described as "Islam" and he says his personal goal is "career and money."
Tim Kelleher, a wrestling coach for a Boston school that competed in 2010 against Dzhokhar's team, said the young man was a good wrestler, and that he'd never heard him express any political opinions.
"He was a tough, solid kid, just quiet," said Kelleher, now a Boston public school teacher.
Deana Beaulieu, a 20-year-old student at Bunker Hill Community College who lives two blocks away from the suspects' home on Norfolk Street, said she went to high school with Dzhokhar and was friendly with his sister. She hadn't seen him since they graduated in 2011.
Speaking on the corner of Norfolk Street, she said she first met the younger brother in 2006 when she started seventh grade at the Cambridge Community Charter School and visited the family at their second-floor apartment that year. She recalled meeting the parents there.
"He was just a quiet kid," Beaulieu said of Dzhokhar, noting that she doesn't recall his ever expressing any political views. "I thought he was going to branch off to college, and now this is what he's done. ... I don't understand what the hell happened, what set him off like this."
Dzhokhar appeared in the video released by authorities on Thursday, identified as Suspect Number 2, striding down a sidewalk, unnoticed by spectators who were absorbed in the race. He followed Tamerlan by about 10 feet. He wore what appeared to be a gray hoodie under a dark jacket and pants, and a white baseball cap facing backward and pulled down haphazardly.
Tamerlan was wearing khaki pants, a light T-shirt, and a dark jacket. The brim of his baseball cap faced forward, and he may have been wearing sunglasses.
According to the website spotcrime.com, Tamerlan was arrested for domestic violence in July 2009, after assaulting his girlfriend. That report could not be immediately confirmed.
He was an amateur boxer, listed as a competitor in a National Golden Gloves competition in 2009. In a local news article in 2004, someone identified as Tamerlan spoke about his boxing and his views of America.
"I like the USA," Tamerlan was quoted as saying in The Sun of Lowell, Mass. "America has a lot of jobs. That's something Russia doesn't have. You have a chance to make money here if you are willing to work."
The paper quoted Tamerlan's trainer, Gene McCarthy, as saying: "He has a lot of heart. That's the key." It said he loved music, and played the piano and violin.