Representative Issa and Senator Grassley released a joint report [pdf] on their investigation into the ATF's Fast and Furious operation. It covers their recent interviews with ATF officials in Mexico.
Acting ATF Attaché Carlos Canino gave his thoughts on the situation:
You don't lose guns. You don't walk guns. You don't let guns get out of your sight. You have all these undercover techniques, all these safety measures in place so guns do not get out of your custody or control. I mean, I mean, you could follow, you could do a surveillance for 1,000 miles . . . either use planes, trackers, you use everything under the sun, but at the end of the day, those guns do not leave your control. At some point those guns do not get into the streets.
Law enforcement is known to let drugs and other contraband "walk" from time to time if a minor infraction might lead them upstream to the bigger fish. However, there is one hard and fast exception: you never let guns go. The agents who authorized and conducted Fast and Furious knew this, and chose to take the risk.
Walking away from one, walking away from one gun when you know that that gun is going to be used in a crime when you, I mean, there is no, there was no gray area here guys. There was no gray area here. We knew that these guys were trafficking guns into Mexico. There is no gray area.
He also implicates Mark Chait, Assistant Director of Field Operations. Mario Gonzalez Rodriguez was murdered by Sinaloa cartel members, who were later found to be in possession of guns traced back to Fast and Furious. By his account, Canino sought to address the matter with Chait, but was prohibited from telling officials in Mexico of this connection.