More gunwalker questions for Attorney General Holder

Newly-released documents show that last February, on an official visit to Mexico, Justice Department official Lanny Breuer suggested fighting arms trafficking by using the tactic of intentionally letting guns flow into Mexico via criminals.

According to the documents, Assistant Attorney General Breuer suggested the U.S. and Mexico consider working together to allow arms traffickers for Mexican drug cartels "to cross into Mexico," so that Mexican authorities could later prosecute and convict them.

The documents indicate Mexico's then-attache spoke against Breuer's idea. He "raised the issue that there is an inherent risk in allowing weapons to pass from the US to Mexico; the possibility of the [Government of Mexico] not seizing the weapons; and the weapons being used to commit a crime in Mexico."

The mere suggestion by a high level Justice official that "gunwalking" should be employed raises eyebrows not only because the tactic is considered dangerous, and has since been officially banned by Attorney General Holder; but also because of the timing. The Justice Department had just drafted a letter to Congress denying it would ever use such a tactic. And Congress had just begun investigating the ATF gunwalking operation "Fast and Furious," which had been operating in secret for more than a year.

There's no indication in the documents as to whether Breuer knew at the time of his suggestion that a major gunwalking operation had already been underway for more than a year.

In recent months, Breuer acknowledged he knew of a gunwalking operation called "Wide Receiver" begun under the Bush Administration. Breuer said he never informed Holder that gunwalking had been allowed, even after the controversy over Fast and Furious surfaced.

The idea in Fast and Furious and other gunwalking operations conducted secretly by government agents in recent years was to try to see where the guns ended up, and catch the "big fish" of a Mexican drug cartel. According to law enforcement sources, Mexican officials were not in on the plan, and no arrests of top cartel members ever happened.

Instead, thousands of guns were let into the hands of criminals where they were sometimes used in attacks on innocent people including Border Patrol Agent Brian Terry. Terry was murdered in an attack near the Mexican border in December 2010, two months before Breuer made the official suggestion to coordinate with Mexico on allowing guns to flow across the border.

In response to the new documents, Justice Department officials say Breuer's suggestion was made in the spirit of combating Mexican drug cartels.

Attorney General Eric Holder appears Thursday before the House Oversight Committee.

Sharyl Attkisson

Sharyl Attkisson is a CBS News investigative correspondent based in Washington.

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