[Yahoo] A firing squad in South Carolina executed Brad Keith Sigmon on Friday for the beating deaths of his ex-girlfriend's parents, marking the first firing squad execution in the state in modern history and the first in the U.S. since 2010.Sigmon was strapped to a specially made chair and had a hood over his head while three volunteer corrections staffers aimed loaded rifles at his heart and each fired off live rounds, according to several news media witnesses who spoke at a news conference afterward. He was pronounced dead at 6:08 p.m., the witnesses said.