CALLAWAY — Libby Busbee pounded on the window of her son’s maroon Dodge Charger as he sat in the driveway of their home earlier this year. Locked inside his car, U.S. Army Spc. William Busbee sat with a .45-caliber gun pointed to the side of his head. “Look at me,” his mother cried out as she tried to get her son’s attention. “Look at me.” He wouldn’t look. He stared out the front windshield, distant, Busbee said, relating the story from an apartment complex in Callaway. “I kept yelling, ‘Don’t you do this. Don’t do it.’ He wouldn’t turn his...