The ATF is accused of running an operation it called "Fast and Furious" that allowed cartel gun buyers to purchase weapons and take them unhindered into Mexico.
"Clearly the concern is that a weapon, two weapons, were found at the homicide scene where Brian Terry was murdered and that those weapons had been part of Operation Fast and Furious."
Despite some recent reforms, some states say the "Secure Communities" program is making their policing efforts more difficult.
Agents from the bureau of Alcohol, Tobacco and Firearms testified they tried to stop the gun walking program.
The fact is that when you buy pot on the black market, there's usually no way to know where it came from.
New Juárez Police Chief Julian Leyzaola promises to restore order in the city and win the trust of its citizens.
Department of Homeland Security officials said it was only in a preliminary research phase.
Arizona Attorney General Tom Horne said authorities are still looking for the ringleader, who is at large in Mexico.
Federal agents arrested the father-son owners of a popular string of restaurants in Arizona and California, Wednesday morning. They are accused of hiring illegal immigrants and paying them under the table.
After three weeks of patrolling county lines by aircraft, Sheriff Joe Arpaio says he plans to scrap Operation Desert Sky in which volunteers have boarded their own airplanes to look for drugs and smugglers crossing the Maricopa County Border.