~excerpt~FAYETTEVILLE, Arkansas (AP) -- A federal jury convicted a 23-year-old man on an obscure weapons charge Tuesday, apparently unaware that 10 years ago he and another boy killed four classmates and a teacher in a schoolyard ambush. Mitchell Johnson, who killed classmates and a teacher 10 years ago, was convicted of a gun charge Tuesday. Mitchell Johnson faces 10 years in prison and a $250,000 fine when he is sentenced in the next 45 days on a count of possessing a firearm while being a drug user. Through his attorney, Johnson declined to comment Tuesday. Johnson was arrested on New...