One of the best articles I found regarding Tamerlan and his boxing career was in the New York Times.
http://www.nytimes.com/2013/04/28/u...rlan-tsarnaev-reeled.html?pagewanted=all&_r=0
A Battered Dream, Then a Violent Path
By DEBORAH SONTAG, DAVID M. HERSZENHORN and SERGE F. KOVALESKI
Published: April 27, 2013
BOSTON — It was a blow the immigrant boxer could not withstand: after capturing his second consecutive title as the
Golden Gloves heavyweight champion of New England in 2010, Tamerlan Anzorovich Tsarnaev, 23, was barred from the national Tournament of Champions because he was not a United States citizen.
The cocksure fighter, a flamboyant dresser partial to white fur and snakeskin, had been looking forward to redeeming the loss he suffered the previous year in the first round, when the judges awarded his opponent the decision, drawing boos from spectators who considered Mr. Tsarnaev dominant.
From one year to the next, though, the tournament rules had changed, disqualifying legal permanent residents — not only Mr. Tsarnaev, who was Soviet-born of Chechen and Dagestani heritage, but several other New England contenders, too. His aspirations frustrated, he dropped out of boxing competition entirely, and his life veered in a completely different direction.
Mr. Tsarnaev portrayed his quitting as a reflection of the sport’s incompatibility with his growing devotion to Islam. But as dozens of interviews with friends, acquaintances and relatives from Cambridge, Mass., to Dagestan showed, that devotion, and the suspected radicalization that accompanied it, was a path he followed most avidly only after his more secular dreams were dashed in 2010 and he was left adrift."
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"As it happened, Golden Gloves of America was just then changing its policy. It used to permit legal immigrants to compete in its national tournament three out of every four years, barring them only during Olympic qualifying years, James Beasley, the executive director, said. But it decided in 2010 that the policy was confusing and moved to end all participation by noncitizens in the Tournament of Champions."
Much much more in the article...