the 58 year old will become the first person in the us to be executed using nitrogen gas, a method which the united nations has called cruel and inhumane . it will be the state s second attempt to execute smith, who was convicted in 1989 of murdering a preacher s wife, in a hired killing. tom bateman reports. they have a 12 hour window basically from six o clock local time in alabama until six o clock in the morning to carry out this untested and experimental as it has been described by its many detractors method and that will involve kennett smith being led into the execution chamber, having an airtight mask strapped to his face and then pure nitrogen pumped from a pressure ride tank and him being effectively asked to breathe it in. they have of course been many experts suggesting that one of the problems here is this has never been done before. essentially we heard from what of your contributors there, soby contributors there, soby contributors there, soby contrib