MELISSA BLOCK, host:
This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.
Last year, a U.S. Border Patrol agent was shot to death in Mexico, and now, evidence from that killing has touched off a scandal here in Washington. Two weapons found at the scene of Brian Terry's death have been traced to a U.S. government program. It deliberately allowed hundreds of guns from the U.S. into Mexico in an effort to track down traffickers.
As NPR's Carrie Johnson reports, Republicans in Congress are asking what the Justice Department knew about the program.
CARRIE JOHNSON: Investigators at the Bureau of Alcohol, Tobacco and Firearms called it Operation Fast and Furious, just like the blockbuster movie. Agents wanted to follow the flow of guns from the U.S. into the hands of deadly Mexican drug cartels, but the only thing that's coming fast and furious now are hostile questions from Congress.
Attorney General Eric Holder, who oversees the ATF, tried to explain what he knew about the episode on Capitol Hill this week.
Mr. ERIC HOLDER (Attorney General): You have to understand the way in which the department operates. Although there are operations, this one has become - has gotten a great deal of publicity.
Representative DARRELL ISSA (Republican, California; Chairman, House Oversight and Government Reform Committee): Yeah, there are dead Americans as a result of this failed and reckless program, so I would say that it hasn't gotten enough attention.
JOHNSON: That was California Republican Darrell Issa. He leads the House Oversight Committee. He's trying to uncover how the gunrunning investigation went off the rails and whether top Justice Department leaders approved it in advance.
To find out more, congressional investigators have traveled to Arizona. That's where people working with drug gangs illegally purchased more than 1,000 guns. Many of those guns were later found at crime scenes on both sides of the border.
Iowa Republican Senator Charles Grassley has been on the trail too.
Senator CHARLES GRASSLEY (Republican, Iowa): At best, the ATF was careless in authorizing the sale of thousands of guns to straw purchasers. At worst, our own government knowingly participated in arming criminals, drug cartels and those who later killed federal agents.
JOHNSON: Federal agents like Brian Terry. He died in a hail of gunfire in Mexico last December. Two U.S. assault weapons were found nearby. Authorities traced those weapons to illegal gun purchases at a dealership in Arizona. The transactions were carried out while ATF investigators watched.
No one has been charged in agent Terry's death, and the investigation continues.
The Justice Department's internal watchdog is investigating too, but that probe is focused on the department's own people and whether they violated their mission to prevent the flow of guns.
For his part, Attorney General Holder said he hadn't been aware of the operation. He told lawmakers it's on his radar screen now.
Mr. HOLDER: What I have told people at the Department of Justice is that under no circumstances, in any case, that any investigation that we bring, should guns be allowed to be distributed in an uncontrolled manner.
JOHNSON: Congressional Republicans say more than a dozen whistle-blowers have come forward to express their concerns about the danger of Fast and Furious. That includes ATF agents, their supervisors and even an Arizona gun dealer.
The unnamed dealer sent emails to agents in Arizona last year, six months before Brian Terry's death, warning them he had a bad feeling. In the messages, the dealer said he was worried the guns would make their way to Mexico and be used by bad guys.
Justice Department officials say the operation was approved by the top federal prosecutor in Phoenix and ATF officials there. They say investigators needed more evidence to build a case against higher-ups like middlemen and drug cartel leaders.
In an exchange with Congressman Issa, Holder bristled at the suggestion those investigators have blood on their hands.
Mr. HOLDER: The notion that somehow or rather this Justice Department is responsible for those deaths that you mentioned, that assertion is offensive. And I want to tell you that...
Rep. ISSA: But what if it's accurate, Mr. Attorney General?
JOHNSON: Republican lawmakers say the Justice Department is holding back documents and stonewalling their attempts to find out more about Fast and Furious. But department leaders say they can't turn over all their materials because of the ongoing criminal investigation.
Carrie Johnson, NPR News, Washington.