NEW YORK—Witnesses reported that a tense, grim silence fell over the cafeteria of the Metropolitan Correctional Center Monday as inmate No. 61727-054, Bernard Madoff, repeatedly stabbed a sharpened toothbrush into the jugular vein of his cellmate, Donald Orlando. Facing a life sentence for securities fraud, Madoff, 70, was reportedly restrained by six guards after he nearly decapitated Orlando with a series of vicious, powerful jabs to his throat. "That guy's loco, man," fellow prisoner Luis "Viper" Ortiz said. "Donnie should never have disrespected him. Everyone in here knows you don't cross Mad Dog." Officials would not confirm whether Madoff was responsible for a brutal incident last week in which an inmate was forced to bite down on a shower faucet and then repeatedly kicked in the back of the head.