A murderer who killed a preacher's wife in 1988 is set to become the first death row inmate in America to be executed with nitrogen. Alabama officials want to put Kenneth Eugene Smith, 58, to death by nitrogen hypoxia - forcing him to breathe only nitrogen, depriving them of oxygen and causing them to die. Several states have authorized the method, which is said to be painless, but it has still never been used. Critics have said authorities would be 'experimenting with a never before used method - but even Smith has said he would prefer death by nitrogen to...