Officials in charge of the Bureau of Alcohol, Tobacco and Firearms' (ATF) operation know as “Fast and Furious” apologized for mistakes made and said they would have done things differently if given a second chance. They said that the investigation was designed to destroy a large-scale arms smuggling operation from Phoenix to Mexico. Guns linked to the operation had been found at crime scenes in Mexico and the U.S., including the scene of a border agent killing in rural Arizona. ATF agents based in Mexico also testified, saying they could not understand why their agency permitted an operation that that eventually armed Mexican drug cartel members.