Complex sentence: Her nine-year-old niece, Minnie Lee Langley, had witnessed Aaron Carrier taken from his house three days earlier; when Langley heard someone had been shot, she went downstairs to find her grandmother, Emma Carrier.
Split into simpler sentences: Her nine-year-old niece at the house, Minnie Lee Langley, had witnessed Aaron Carrier taken from his house three days earlier. When Langley heard someone had been shot, she went downstairs to find her grandmother, Emma Carrier.