this ray ruth now in custody facing murder charges. we are learning he was a marine. served in iraq as well. chris kyle reportedly was helping him deal with post-traumatic stress disorder. kyle wrote the best selling book american sniper. the autobiography of the most lethal sniper in u.s. military history. it documented his time in uniform. last january, you may have seen it kyle appeared on the o'reilly factor. bill asked him about the gravity and consequences of his job. >> so you were committed to killing these people because you in your heart believe that they deserve to die? >> i wasn't so much committed to killing them as i was i'm committed to making sure every service member that was over there, whether american or allied came home. >> bill: but as a sniper your job is to kill them. not wound them, not arrest them. you have to have a certain mentality to be a sniper. you are killing them. >> oh, i'm killing them to protect my fellow americans.