In the world's first known execution by nitrogen hypoxia, the US state of Alabama put to death Kenneth Eugene Smith, a prisoner on death row for his role in a contract killing more than three decades ago, The Washington Post reported.
Washington DC [United States] March 15 (ANI): The officials of the US State Oklahoma have announced to use nitrogen gas as a preferred method of execution, when it resumes using the death penalty, making it the first US state to do so.