Alabama executes third man this year with controversial nitrogen gas

Carey Dale Grayson was killed on Thursday for 1994 murder by technique that previously caused visible signs of distress

Alabama carried out its third execution this year using the controversial new method of nitrogen gas, a technique that in previous state killings caused visible signs of distress.

Carey Dale Grayson was put to death on Thursday evening for the 1994 murder of a hitchhiker. The prisoner had a mask strapped to his face through which nitrogen was pumped, causing fatal oxygen deprivation.