That smirk. There was something disturbing about the way Paul Littlejohn, just a teenager, wore it at his sentencing, the way it radiated an attitude impervious to his circumstance: He shuffled through the courthouse corridors in shackles on his way to prison, possibly for the rest of his life, for his role in the shooting of a 3-year-old boy. Sharletta Evans, the toddler’s mother, could not forget his expression — a mask of carelessness that, in her eyes, trivialized the loss of her precious Casson in the 1995 drive-by shooting that marked another in a litany of tragedies with roots in Denver’s “summer of violence” two years earlier. “I could not shake that smirk,” Evans recalls now.