The truth about the Fast and Furious scandal

June 27, 2012: 5:00 AM ET

A Fortune investigation reveals that the ATF never intentionally allowed guns to fall into the hands of Mexican drug cartels. How the world came to believe just the opposite is a tale of rivalry, murder, and political bloodlust.

By Katherine Eban

FORTUNE -- In the annals of impossible assignments, Dave Voth's ranked high. In 2009 the federal Bureau of Alcohol, Tobacco, Firearms and Explosives promoted Voth to lead Phoenix Group VII, one of seven new ATF groups along the Southwest border tasked with stopping guns from being trafficked into Mexico's vicious drug war.

Some call it the "parade of ants"; others the "river of iron." The Mexican government has estimated that 2,000 weapons are smuggled daily from the U.S. into Mexico. The ATF is hobbled in its effort to stop this flow. No federal statute outlaws firearms trafficking, so agents must build cases using a patchwork of often toothless laws. For six years, due to Beltway politics, the bureau has gone without permanent leadership, neutered in its fight for funding and authority. The National Rifle Association has so successfully opposed a comprehensive electronic database of gun sales that the ATF's congressional appropriation explicitly prohibits establishing one.