Kenneth Eugene Smith has become the first person in history to be executed with nitrogen gas. The convicted killer, 58, was put to death in the William C. Holman facility's execution chamber in Atmore, Alabama. After the reading of his last rights, a tight gas mask was placed over Smith's nose and mouth, before a stream of 100 percent nitrogen gas suffocated him. The gas mask remained on his face for 15 minutes to ensure the murderer was dead. Witnesses were led into the viewing room at 6:55pm, and Smith was pronounced dead half an hour later. Despite fears over...