FRANCONIA, N.H. -- Judging from his history of gunplay and boasting about violence, detailed in court records, Gregory W. Floyd was a tinderbox waiting for a spark. The moment came last Friday, when the 49-year-old former Marine jumped into the middle of a deadly shooting, grabbed the gun from a dying policeman, and killed the man , Liko Kenney, 24, who had shot the officer. Now Floyd is being hailed as a hero. But police reports, neighbors, and acquaintances paint a more complex portrait of a man who lived by his own code, and whose past, as much as his...