federal border patrol agents stopped two men driving a car through the border-crossing town of Columbus, New Mexico. Inside the vehicle was a cache of assault weapons, including AK-47s, Ruger .45-caliber handguns and pistols called "cop killers"

federal border patrol agents stopped two men driving a car through the border-crossing town of Columbus, New Mexico. Inside the vehicle was a cache of assault weapons, including AK-47s, Ruger .45-caliber handguns and pistols called "cop killers" because their ammunition can penetrate armor.

The U.S. Customs and Border Protection officers ran the guns' serial numbers in a nationwide database and waited. None of the eight came back flagged as stolen or suspect, so the agents let the men go — just a few short miles from the Mexican border, where gun trafficking is fueling a violent and deadly drug war.

At the time, the border guards were unaware that six of the weapons had been purchased by alleged straw buyers in a federal sting and were supposed to be monitored by Bureau of Alcohol, Tobacco, Firearms and Explosives agents trying to bust a major Mexican gun running ring.

The ATF had not yet flagged the weapons in a law enforcement database, and CBP wouldn't alert its sister law enforcement agency to the traffic stop for five months, delays that would prove fateful for both agencies.

Posted in: federal border patrol agents