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.