The rise and fall of a top Chicago mobster, by ex-FBI agent Roemer (War of the Godfathers, 1990). Roemer traces the life of nasty, brutish, and short Tony ``The Ant'' Spilotro, who rose from humble beginnings on the west side of Chicago to rule the West (including Las Vegas) for the Chicago crime syndicate in the 1970s and early '80s. He describes Spilotro's apprenticeship with loan shark ``Mad Sam'' DeStefano (a man Roemer questionably dubs ``the worst torture-murderer in history''); his years as hit man and ``whiz-kid'' under Felix ``Milwaukee Phil'' Alderisio, boss of the Chicago mob; and his promotion in 1971 to ``representato'' in Las Vegas, a post that included overseeing the skimming operations at top casinos and running the ``Hole-in-the-Wall Gang,'' which preyed on hotel patrons, stores, and homes. Finally, in 1986, just as he faced yet another retrial for burglary and racketeering, Spilotro was gunned down by order of the new boss, Joe Ferriola. Roemer's book has its fascinations, including a ``primer on how to skim'' and lessons on how to insult mobsters (try ``slime'' and ``scum,'' he suggests; ``eleven- and twelve-letter names [don't] seem to faze them''). But the author professes an Ahab-like obsession with his subject that doesn't quite hold up: After all, Roemer was assigned to shadow a different mobster, and his own encounters with Spilotro were limited to infrequent exchanges of name-calling. As a result, Spilotro's character, such as it was, remains a cipher. Less forgivably, the author's prose sounds as if it were ad-libbed into a dictating machine (``So it was that Tony fled from Chicago. Fled is the wrong word''), and the dialogue, which he freely admits he has ``reconstructed,'' often rings false. Best for addicts of the genre.