WHISTLE-BLOWERS COME IN ALL different styles, but they don't tend to be the boss's choice to inherit the top job. Mark Whitacre, 38, was just such a favorite at giant Archer Daniels Midland, the company that calls itself "supermarket to the world" because its products range from flour to vegetable oil. So close was Whitacre to ADM chairman Dwayne Andreas that the older man regarded the younger as a "second son." And as if to emulate his mentor, Whitacre lived in a colonial-style mansion in Moweaqua, Illinois, that Andreas once owned.
But the heir apparent was leading a double life. To...