[link to edition.cnn.com]

At first they said he was drunk, but no mention now of that.

...
"There was new information Monday about the soldier accused of the killings. A Department of Defense official told CNN the man, a staff sergeant, was a qualified infantry sniper, trained to hit to kill at about 800 meters. He had spent three tours of duty in Iraq, where he suffered a traumatic brain injury in a 2010 vehicle accident.

But village tribal leaders said their people can't comprehend how a trained professional soldier could have acted alone and done such a thing."