The popular resort town of Mazatlan, known for its fine beaches and relaxed pace, has begun to feel the sting of organized crime. Two federal judges and one of their wives were gunned down Nov. 18 outside a colleague’s home while waiting to go to a ballgame. The killing of judges represents an ominous step in a rising climate of insecurity in Mexico, and the incident in Mazatlan, a place which previously had seemed immune from such troubles, has raised fears that the area’s sleepy isolation may be ending. Such a development wouldn’t by itself affect a tourist’s visit here, but it could dampen the general atmosphere.