RIVERTON, Wyo. (AP) — A 51-year-old man has pleaded not guilty to charges that he shot his wife to death in front of the couple's children on the Wind River Indian Reservation. The Ranger in Riverton reports that Koby Dean Johnson entered his plea Thursday to a first-degree murder charge. A trial is scheduled to begin Feb. 16 in Casper before U.S. District Court Judge Scott W. Skavdahl. Johnson is accused of the Nov. 21 shooting of 36-year-old Rachael Noel Johnson, who was a nursing student at Central Wyoming College.