EXCLUSIVE: Two guns sold to a Mexican cartel and used in the high-profile kidnapping and murder of a Mexican lawyer last year were purchased under the U.S. Justice Department's failed anti-gun trafficking program Operation Fast and Furious, sources tell Fox News.

U.S. law enforcement sources and officials in Washington told Fox News that two AK-47s were purchased in Arizona by a straw buyer — someone who legally buys guns, then illegal sells them to a third party – and were allowed to “walk” into Mexico. Police recovered the guns in the course of their investigation of the kidnapping of Mario Gonzalez Rodriguez.

Gonzales, brother of the now former attorney general of Chihuahua, Patricia Gonzalez Rodriguez, was kidnapped in October. He was taken by six gunmen from the Sinaloa cartel and tortured extensively over two weeks.

Three videos posted online show Gonzalez surrounded by hooded armed men with his hands and feet bound and apparently being electrocuted with electrical devises attached to his feet.

The incident received heavy publicity in Mexico – not just because he was a family member of a top law enforcement officer, but because he claims in the video that his sister, while attorney general, protected the Juarez cartel, and that she ordered the murder of two journalists and a member of the Mormon community in that state.

His sister went on national TV and denied the claims and said the kidnappers belonged to the rival Sinoloa cartel.

Gonzalez’s body was found last November in a shallow grave outside the city after armed federal police forces raided the kidnappers' compound. Mexican officials arrested the suspects and confiscated the guns.

According to Fox News sources, Mexico was not told the confiscated guns were part of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives’ Operation Fast and Furious until the past week.

Federal and Chihuahua state attorney general officials in Mexico have not responded to Fox News' request for comment. The ATF in Washington would not comment on the record for this report, except to say it is investigating the claim.

Mexico submits thousands of guns for tracking in the U.S. by serial number.

Fast and Furious, which was supposed to trace and stop the trafficking of illegal guns, instead allowed thousands of guns get into the hand of Mexican cartel members.

The program is now the focus of an investigation by the House Oversight and Government Reform Committee.

On Wednesday, ATF Special Agent John Dodson testified that the operation facilitated the sale of about 2,500 firearms. About 700 have been recovered by police at crime scenes in Mexico and the U.S., but he said that there could be as many as 1,800 of them still out.

Until now, the most high-profile crime allegedly committed with these guns was the murder in December of U.S. Border Patrol Agent Brian Terry. Two guns found near his body in Mexico were traced to the ATF program, though it is unclear if they were the guns that killed Terry.

President Obama and Attorney General Eric Holder have tried to distance themselves from the failed program, saying it was running without their approval.

On Friday, White House broke its silence for the first time since the hearings exposed the extent of the failed program.

When asked about Operation Fast and Furious and the contention that the administration deliberately sent these guns south, White House Press Secretary Jay Carney said the president did not know who authorized the program.

“I can tell you that, as the president has already said, he did not know ... about or authorize this operation. But the Department of Justice has said repeatedly that fighting criminal activity along the Southwest border, including the illegal trafficking of guns to Mexico, has been and is a priority of the department,” Carney said.