Kenneth Eugene Smith has become the first person in history to be executed with nitrogen gas. The convicted killer, 58, had a tight gas mask placed over his nose and mouth before a stream of 100 percent nitrogen gas suffocated him inside the execution chamber at the William C. Holman prison in Atmore, Alabama. Smith was officially pronounced dead at 8:25 local time, following a 22-minute ordeal where he appeared to remain conscious for several minutes. He shook violently and pulled on the restraints on the gurney, continuing to breathe the nitrogen gas heavily until he succumbed and passed out....