A man charged with firing off more than 100 rounds from an AK-47, killing 46 year old Charles J. Christian and seriously wounding 32 year old Phyllis H. Avery in 2007 will likely spend the rest of his life in a mental institution.  John Clayton Corley entered a plea of not guilty by reason of insanity Thursday.  The plea was accepted by Floyd Superior Court Judge J. Bryant Durham and was not contested by the DA’s office.  A psychological evaluation showed Corley was suffering from delusions at the time of the crime.  Apparently, Corley felt as though he was under the influence of an alien being.