Two people have been charged with murder in the killings of a couple whose remains were found scattered around Long Island in late February and early March. Jeffrey Mackey and Alexis Nieves pleaded not guilty on Monday to killing Malcolm Brown and Donna Conneely, of Yonkers. Mackey, Nieves and two other people were previously charged with concealing a human corpse and tampering with evidence in connection with the discovery of body parts in Long Island parks. Christopher Gioe, an attorney for Nieves, said she maintains her innocence. Mackey's attorney says he will fight the charges.