PIKETON, Ohio >> From her house on Union Hill Road, Brittany Barker heard the first sirens first thing in the morning. She looked out and saw four police vehicles rush past. That was only the beginning."They just kept coming, kept coming, and kept coming," she recalled.Authorities in this struggling corner of Appalachia were dealing with what turned out to be one of the worst mass killings in Ohio history: Eight family members were shot to death at four homes scattered across a few miles of countryside in what investigators have portrayed as a meticulously planned "execution.