'I teach a guy to fight, not kill'
A couple miles from the family home is the Somerville Boxing Club. Hundreds of boxers have come through the doors over the years. Trainer Gene McCarthy has been there for three decades and remembers the day Tamerlan, then 16, walked in with his father.
The dad was an amateur boxer in Chechnya and wanted his oldest son to get even better training. Tamerlan was a physical specimen: 6-foot-3 and 196 pounds. He had a long reach, great quickness, tenacity and confidence -- the perfect combination of a young Muhammad Ali.
He wouldn't just knock out his opponents; he would annihilate them. "When he threw a punch, he was always right on the money, right on the target," McCarthy said. "Nobody could touch him."
After winning one fight in January 2004, the rising sensation told the Lowell Sun newspaper that he grew up in Grozny, Chechnya, and moved with his family to the United States the year before in hopes of starting a new life.
"I like the USA," Tamerlan said. "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."
McCarthy ranks him as one of the best fighters he's ever trained. He won the open class heavyweight division for the New England Golden Gloves. The kid could've taken a gold medal at the Olympics, he said, but his immigration status prevented him from trying out for the U.S. Olympic team.
"I would say, 'Geeze, I've got an Olympic champion but he can't qualify,' " McCarthy said. "That was his only downfall -- the fact he wasn't a citizen. ... He had the gumption and everything to win it all. He was fearless."
At the gym, the younger brother, then just 10, would tag along and do calisthenics with Tamerlan. "He was a cute little kid," McCarthy said.
He recalled registering Tamerlan at the Golden Gloves. "While he was waiting in line, he saw a piano and was playing classical music like it was Symphony Hall," McCarthy said. "Everybody in USA Boxing heard it, and they went in there and they were amazed."
Boxers in his gym typically come from troubled backgrounds -- broken families, crime-ridden neighborhoods, absentee fathers. That wasn't the case with Tamerlan who had a solid family support system. His mother, father and younger brother would come to the fights. He went undefeated in his two years with McCarthy.
McCarthy tries to instill self-respect and discipline in his fighters. "That's what boxing means to me," he said. "Train them that, and they can become respectable people -- believe it or not."
His emotions ranged from anger to dismay when he learned the brothers were suspects in the bombings. "I teach a guy how to fight, not kill," he said.
McCarthy sighed. Tamerlan was such a likable person; the only people who didn't like him were the guys he beat to a pulp in the ring.
"He was just a young kid then, and that's about all I can say as far as that goes. I can only say nice things about him."
Tamerlan switched to a different gym after two years. They didn't have a dispute, McCarthy said. It's just the way it goes in the rolling stone life of boxing. The kids come and go.
Yet Tamerlan didn't give up his dream. He registered again with USA Boxing from 2008-2010, but he never regained his undefeated form.
In 2009, his uncle Ruslan Tsarni had a falling out with Tamerlan. "I got into really a state of shock from changes I heard -- I wouldn't say I saw -- I heard from Tamerlan," he told CNN.
The uncle recalled a phone conversation in which Tamerlan called him an "infidel." The young man also told his uncle he was not concerned about work or studies because God had a plan for him.
Soon, Vasquez said, he vanished from his neighborhood. "I wonder what happened in that time we stopped seeing him around."
'I think his brother put him up to it'
If Tamerlan was the reserved one, Dzhokhar -- known as "Jahar" -- was the outgoing kid, always quick with a joke. That was one of his goals, his friends say, to make them laugh. The only time they'd seen him mad was if he lost a wrestling match. Even that was rare. He was an all-star, 135-pound wrestler who placed in the state finals.
One friend remembered seeing how happy Dzhokhar was at the TD Bank Garden arena last year when he became an American citizen. It was an especially patriotic day for those in attendance because the ceremony was held on September 11, 2012, a date that seems tragically odd in retrospect.
"Right now, it's like a big puzzle and we're trying to put pieces together," said one family friend who asked not to be identified.
Dzhokhar was kind-hearted, too. When he wasn't wrestling in high school, he volunteered at an after-school program to help kids with autism and Down syndrome.