DEVELOPING: No one has been punished “yet,” Attorney General Eric Holder said Thursday in a contentious hearing on the role of the Justice Department in “Operation Fast and Furious,” about which Holder insisted once more he only heard about in the winter of 2011.

The hearing comes after House committee chairman Rep. Darrell Issa, R-Calif., asserted that top Justice officials are covering up events surrounding the flawed gun-smuggling probe. 

Issa made the accusation in a letter threatening to seek a contempt of Congress ruling against Holder for failing to turn over congressionally subpoenaed documents that were created after problems with Fast and Furious came to light. 

In his testimony Thursday before the House Oversight and Government Reform Committee, Holder reaffirmed his “commitment to ensuring that these flawed tactics are never used again.”

Holder said that “allowing guns to ‘walk’ — whether in this administration or in the prior one — is wholly unacceptable.” 

“The tactic of not interdicting weapons, despite having the ability and legal authority to do so, appears to have been adopted in a misguided effort to stem the alarming number of illegal firearms that are trafficked each year from the United States to Mexico,” he said. 

Holder told the committee, “I’m not sure exactly how I found out about the term, ‘Fast and Furious.’ ” He testified repeatedly that he never authorized the controversial tactics employed in the operation. 

“There is no attempt at any kind of cover-up,” Holder said under questioning. “We have shared huge amounts of information” and will continue to do so, he said. 

But Holder’s statements on the Justice Department’s role in the operation did not sit well with Republican lawmakers on the committee, who accused the attorney general of intentionally withholding key documents in the case. 

“The conclusion that I come to is there are some things in there that’s being hidden that you don’t want us to see,” said Rep. Dan Burton, R-Ind. “We have every right under the Constitution to check on what you’re doing… So for you to deny this committee anything like that is just dead wrong and I don’t think you’re going to find any way that you can do it.” 

Burton went on to say that there are 93,000 documents related to the operation that are being withheld by the Justice Department.

“And you’re saying, well the separation of powers prohibits you from doing that. That’s baloney. That is just baloney,” Burton said. 

Issa told Holder the committee will do what is necessary to obtain the information, “If you do not find a legitimate basis to deny us the material we’ve asked for.”

Holder said earlier during testimony that he would release additional materials “to the extent that I can.”

In Fast and Furious, agents lost track of about 1,400 weapons they were tracking after they were sold to low-level straw purchasers believed to be supplying Mexican drug gangs and other criminals. Another 700 firearms connected to suspects in the investigation have been recovered, some from crime scenes in Mexico and the U.S., including a murder scene in Nogales, Ariz., where border agent Brian Terry was killed.

Holder said he learned within 24 hours of Terry’s death.

“When you were informed about that within 24 hours, did anyone inform you or allude to the fact that the weapons found at the scene were from Fast and Furious?” Issa asked Holder.

“No,” Holder replied. “I didn’t know about Operation Fast and Furious until the beginning parts of 2011 after I received that letter from Senator Grassley, I guess at the end of January and then that was about Operation Gun Runner. I actually learned about the Fast and Furious operation in February of that year.”

In Holder’s defense, Rep. Edolphus Towns, D-N.Y., claimed the committee has “not obtained one shred of evidence that would contradict your testimony.”

“Not one witness, not one document, not one e-mail, and still some continue to suggest that you did personally authorize gunwalking and the tactics in Operation Fast and Furious.”