U.S. completes first execution using nitrogen gas

HOUSTON, Jan. 25 (Xinhua) -- The southern U.S. state of Alabama on Thursday night completed the country's first execution using nitrogen gas asphyxiation.

Inmate Kenneth Smith, a 58-year-old convicted murderer, was put to death at 8:25 p.m. local time at an Alabama prison after breathing pure nitrogen gas through a face mask to cause oxygen deprivation, authorities said.