January 12, 2006 -- A bright and talented 7-year-old girl was beaten to death yesterday in her Brooklyn apartment — where she was often tied to a wooden chair — even though child-welfare agents were already probing allegations of abuse, authorities said yesterday. Nixzmary Brown was unconscious and unresponsive when she was found by her mother yesterday morning in their Bedford-Stuyvesant home. Police said the tiny girl was found face up on the floor and had multiple bruises and injuries that were "in various stages of healing." A police source said Nixzmary had bruises on her wrists and ankles, apparently...