A family friend of Audrii Cunningham, the 11-year-old girl whose body was found in a Southeast Texas river, has been charged with capital murder, authorities said Wednesday. Don Steven McDougal, 42, had been previously described as a “person of interest” in the disappearance of Cunningham, who was last seen on the morning of Feb. 15 on her way to school. The girl, who was carrying a bright red “Hello Kitty” backpack, failed to make it to the school bus and never reported to class, school officials told authorities. Her disappearance prompted a massive search in the area that ended with heartbr…