BRIGHTON (CBS) – Tamerlan Tsarnaev was a very talented boxer, according to friends.

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He is believed to have trained at Wai Kru Mixed Martial Arts Gym in the Brighton neighborhood in Boston.

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WBZ-TV’s Jim Armstrong caught up with Tsarnaev’s former trainer Mark Massey on Friday, who describes the man he remembered as a nice guy.

“He’s not the guy I used to know,” Massey said.” (I’m) shocked just like everybody else.”

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Tsarnaev once described himself as not having a single American friend and aspired to be a U.S. Olympic boxer.