It was the odd uniformity of the suitcase’s contents that tipped off the baggage inspector: six thick, identical rectangles. They could have been books, but then again, they could have been six bundles of cocaine. And in August 2007, security was tight at the airport in Buenos Aires; the country was in the midst of a presidential election. It was worth taking a closer look. The suitcase’s owner, a Venezuelan businessman just in from Caracas, hesitated briefly when asked to open his suspicious luggage. Out tumbled $800,000 in cash. It was, according to U.S. investigators, an illegal campaign contribution from…