EDITOR’S NOTE: This account of the investigation into the Louvre heist is based on public statements by prosecutors and museum officials, as well as investigators in France and the United States who agreed to speak with CNN on the condition of anonymity. It was early evening on Saturday, October 25, the surveillance team’s fourth day trailing a 34-year-old Algerian suspect through Seine-Saint-Denis, outside Paris. The work had been tense and tedious. A diverse area, Seine-Saint-Denis is home to