BOSTON -- Friends say Dzhokhar Tsarnaev was a funny kid, an enthusiastic wrestler and a popular graduate of Cambridge's prestigious Cambridge Rindge & Latin School. His elder brother, Tamerlan, took a break from classes at a community college to pursue the sport of boxing -- and said he'd represent the U.S. over Russia in the Olympics if his native Chechnya didn't yet have its independence.
Interviews with friends, teachers, coaches and fellow students Friday painted a portrait deeply at odds with events as a massive manhunt closed down Boston in search of Dzhokhar
Tsarnaev, 19, suspected of carrying out the Boston Marathon bombings Monday with his brother, who was captured in a suburban backyard and taken into custody late Friday.
Tamerlan Tsarnaev, 26, died early Friday after a spectacular overnight crime spree that included the shooting of two police officers and a carjacking.
"This has absolutely floored me," said Thomas Lee, the president of the South Boston Boxing Club, where Tamerlan Tsarnaev trained in 2009 and 2010.
He told McClatchy that the only thing that had set Tsarnaev apart from his fellow boxers was a propensity for offbeat training habits, such as walking around the gym on his hands.
But there were hints Tamerlan was a corrosive influence on his younger brother.
Zaur Tsarnaev, who identified himself as a 26-year-old cousin of the brothers, told the Boston Globe by phone on Friday from Makhachkala, in southern Russia, that he had warned Dzhokhar that Tamerlan "was up to no good."
He said Tamerlan "was always getting into trouble. He was never happy, never cheering, never smiling. He used to strike his girlfriend. He hurt her a few times. He was not a nice man. I don't like to speak about him. He caused problems for my family."
Dzhokhar's friends were at a loss. "This is nothing we would ever expect, ever," said a high school friend, the nephew of Boston radio host Robin Young, who identified himself by the letter "Z."
"He was a laid-back kid you could always count on just to hang out with and really de-stress with," the friend said of Dzhokhar. "There was never a sign of anything out of the ordinary."
Young said the young man made an impression on her when she hosted a prom party for Rindge & Latin's 2011 graduating class.
"I distinctly remember him because he did something risky at one point," she said, describing a teen prank that many high-schoolers might relate to: driving his car backward down her one-way street.
By most accounts, Dzhokhar Tsarnaev was an accomplished student. In May 2011, then a senior at the public high school, he was one of 45 students who received $2,500 scholarships from the city of Cambridge to pursue higher education.
He's enrolled at the University of Massachusetts Dartmouth, which closed Friday after school officials realized he was a student there. A message on the university's website says it "learned that a person being sought in connection with the Boston Marathon bombing has been identified as a student registered at UMass Dartmouth" and that the campus was shut down for the day.
Pamala Rolon, a UMass Dartmouth senior and a resident assistant at the Pine Dale dorms, where Tsarnaev lived, told The Boston Globe she was in shock. She said he studied marine biology and was studious. She also said he hadn't been seen on campus over the past two weeks, but that many students were busy studying.
"I think he's Muslim, but not so religious," she said. "He's a normal city kid."
High school classmate Sierra Schwartz said on ABC that Dzhokhar Tsarnaev "never seemed out of the ordinary at all. This is not someone who seemed troubled in high school or shy. He was just one of us. It's very weird."
Another student said Tsarnaev "always had a positive attitude" and also had some political opinions.
"He always thought the war (Iraq and Afghanistan) was stupid," Steven Owens, who met Tsarnaev in seventh grade, told ABC News. "He didn't enjoy the idea of war. We didn't really talk about it much. The only time it ever really came up was when we were learning about it in school."
The brothers' father, Anzor Tsarnaev, issued a plea for his son to surrender peacefully, and he warned that if his son is killed, "all hell will break loose."
The elder Tsarnaev spoke to ABC News from his Makhachkala home and said he'd spoken to his sons by phone this week: "We talked about the bombing. I was worried about them."
He said his sons were innocent.
Tamerlan Tsarnaev, a talented amateur boxer, competed in the National Golden Gloves in 2009. He told the Lowell Sun in 2004 after winning his first fight that he liked "the USA." But he told a Boston University student who profiled him that despite living in the U.S. for five years, "I don't have a single American friend. I don't understand them."
Still, he told photographer Johannes Hirn, who produced the piece, "Will Box for Passport," as a final project for a photojournalism class, that if he were to become a naturalized American and chosen for the U.S. Olympic team, "he'd rather compete for the United States than for Russia," unless his native Chechnya became independent.
Lee, the boxing club president, described Tsarnaev, a super heavyweight at 6 feet 1 inch and 200 pounds, as a gifted boxer "confident in his abilities" who bounced around the local circuit.
"He was one of those guys, he didn't really plant himself," Lee said. Mostly self-trained, Tsarnaev won the New England Golden Gloves competition in 2009 and advanced to the finals in Salt Lake City.
But illness prevented Tamerlan from competing in the national tournament, and when he tried to return in 2010, Lee said he was told as a foreign athlete wasn't allowed to advance to the national title.
His father told The New York Times that Tamerlan was unable to secure citizenship because of a "scandal" with a girlfriend but that he wasn't disappointed because he "could come and go, arrive and leave as he wished."
The mother of both men, Zubeidat K. Tsarnaeva, told Russia Today that she was "100 percent sure this is a setup, my two sons are really innocent."