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Portrait of Chet Blalock, who moved his martial arts gym from Chattanooga to Fort Oglethorpe, Ga., trained Mohammod Youssuf Abdulazeez. Mr. Blalock said Mr. Abdulazeez was extreme in his training, sometimes allowing himself to be choked to the point of unconsciousness. “It’s a bit on the extreme side, even for mixed martial arts,” Mr. Blalock said. Police say Mr. Abdulazeez killed five military members, four Marines and a Navy sailor, in a shooting rampage on July 16, 2015 in Chattanooga, Tenn. Photo by Kevin Liles for The New York Times