Have you heard about the ATF's 'grenade-walking' scandal?

We know the Bureau of Alcohol, Tobacco and Firearms messed up big time in allowing American guns to be walked into Mexico and placed into the hands of deadly drug cartels. The latest CBS News report from the border, however, reveals that guns weren't the only weapons U.S. officials allowed to fall into the wrong hands.

And like the guns the ATF allowed to be carried into Mexico, the grenades are now popping up in deadly conflicts among cartels.  Sharyl Attkisson has the scoop:

CBS News has learned of a shocking link between a deadly drug cartel shootout with Mexican police last week and a controversial case in the U.S. The link is one of the grenades used in the violent fight, which killed three policemen and four cartel members and was captured on video by residents in the area.

According to a Justice Department "Significant Incident Report" filed Tuesday and obtained by CBS News, evidence connects one of the grenades to Jean Baptiste Kingery, an alleged firearms trafficker U.S. officials allowed to operate for years without arresting despite significant evidence that he was moving massive amounts of grenade parts and ammunition to Mexico's ruthless drug cartels.

The gun battle took place last week in Guadalajara. Authorities say five members of the Jalisco New Generation Cartel used at least nine firearms and ten hand grenades against Mexican police. If one of the grenades was supplied with the help of Kingery, as believed, it adds to the toll of lives taken with weapons trafficked by suspects U.S. officials watched but did not stop.

The Kingery case was overseen by the same Arizona U.S. Attorney and ATF office that let suspects traffic thousands of weapons to Mexican drug cartels in the operation dubbed Fast and Furious. ...

On Wednesday, ATF told CBS News it has "no information" about the Kingery connection to last week's gun battle in Mexico.