A discovery at the hideout of a recaptured Mexican drug lord is linked to an old Washington scandal.

FOX's Eben Brown has details:

Law enforcement combing through the Mexican hideout of cartel king Joaquin Guzman, also known as 'El Chapo' - say they found a .50-caliber rifle once used as bait during the so-called 'Fast and Furious' operation, when U.S. undercover agents sold weapons to criminals hoping to track their movements.

'El Chapo' would have guards use the .50-caliber against law enforcement aircraft surveying them.

That ATF operation had been widely criticized, as weapons ended up being used in violent crimes, including the murder of U.S. Border Patrol Agent Brian Terry.

Eben Brown, FOX News.