Sharyl Attkisson Spotlights New Obama Admin. Scandal: Grenade Running

SHARYL ATTKISSON: Good morning, Norah. Officials from Mexico and the U.S. aren't talking about this link publicly, but sources say they're very concerned behind the scenes. A grenade used in the murders of three Mexican police officers last week has been linked to an alleged arms trafficker that U.S. officials left on the street to operate long after they had evidence of his crimes.

[CBS News Graphic: "Possible U.S. Link To Shootout: Investigating Ties To Alleged Arms Trafficker"]

ATTKISSON (voice-over): The violent gun battle took place last week near Guadalajara (clip of YouTube.com video of shootout) – and was captured on video by area residents. Authorities say five members of the Jalisco New Generation Cartel used at least nine firearms and ten hand grenades against Mexican police. Three policemen were killed, along with four cartel members.

CBS News has learned that one of the grenades has been linked to Jean Baptiste Kingery, a suspected grenade trafficker that U.S. officials had under surveillance for years, but didn't arrest, as he allegedly moved lethal weapons across the border. Wednesday, ATF told us it has 'no information' about the connection. But we've obtained this ATF significant information report, dated Tuesday, stating evidence shows one grenade was a 'Kingery grenade'.

The Justice Department inspector general is already investigating the conduct of federal officials in the Kingery case, which was overseen by the same U.S. attorney and ATF office in Arizona that let suspects traffic thousands of weapons to Mexican drug cartels in the case 'Fast and Furious'. ATF case files show the agency learned back in 2009 that Kingery was dealing in grenades. They developed a secret plan to let him smuggle parts to Mexico, and follow him to his factory. Some ATF agents objected – worried that Kingery would disappear once he crossed the border into Mexico, and that's exactly what happened.

Kingery resurfaced in 2010, trying to smuggle this frightening stash into Mexico, but was again let go, when prosecutors allegedly said they couldn't build a good case. In 2011, Mexican authorities finally raided Kingery's factory and arrested him. He allegedly confessed to teaching cartel members how to build grenades and convert semi-automatic guns to automatic weapons.

ATTKISSON (on-camera): One American official familiar with the investigation into the possible misconduct of U.S. officials for letting Kingery go says the murders of the Mexican police last week is just the latest example of the carnage that continues from U.S. agents allowing guns and grenades to cross the border. And he says both governments are trying to keep the rising death toll quiet. Charlie and Norah?

CHARLIE ROSE: Sharyl, thanks.