58-year-old Kenneth Eugene Smith, convicted for a 1988 murder-for-hire killing, became the first known person to be executed by nitrogen hypoxia on Thursday night. News 19 is North Alabama's News Leader! We are the CBS affiliate in North Alabama and the Tennessee Valley since November 28, 1963. https://whnt.com/ https://www.facebook.com/whntnews19 https://www.instagram.com/whntnews19/ https://twitter.com/whnt