Approximately one hour after Justin Carter posted a sarcastic comment on a Facebook thread, his life began to unravel. The first reaction occurred behind the scenes, in another country. The 18-year-old Carter had no way of knowing that, while he did grunt work at a drapery shop in San Antonio, a person in Canada saw his comments — posted 60 days after the Sandy Hook school-shooting tragedy in Newtown, Connecticut — freaked out and initiated a 24-hour chain reaction of insanity that would wind up with Carter facing 10 years in prison. Carter’s comments were part of a duel between dorks, and may have had something to do with a game with strong dork appeal called League of Legends. But the actual details and context of the online exchange are, in the eyes of Texas authorities, unimportant. Prosecutors say they don’t have the entire thread — instead, they have three comments on a cell-phone screenshot.