'Fast and Furious' Report Not the End of the Issa-Holder Battle

Issa also asked about assertions by "many, mostly on the other side of the aisle, that there's nothing in these wiretap applications that would have caused senior officials to see any red flags as to the reckless tactics."

"As we said in the report, and I also, myself, reviewed the 14 applications, believed that if you were focussed and looking at the question of gun walking, you would read these reports and see many red flags," Horowitz responded.

Cummings focused his questions more on Operation Wide Receiver in the Bush administration. "You also found that neither Attorney General Mukasey nor Attorney General Holder authorized or approved gun walking. Is that right?"

"That's correct, although I would note Attorney General Mukasey was sworn in after the completion of Operation Wide Receiver's investigative portion of the activity," Horowitz noted.

"We have a dead Border Patrol agent, nearly 2,000 AK-47s released, hundreds of dead Mexicans, a Mexican helicopter shot down at one point, a dead Border Patrol agent, hundreds of guns that are still unaccounted for, untold number of crimes that have been committed with these guns, and an attorney general whose best guess and best argument is that -- is the plea of ignorance," said Rep. Jason Chaffetz (R-Utah).

"On guns, if you were so concerned about guns on the border, then my colleagues could have supported the bills that we put forward, the Democrats, to really -- for gun safety. So in my opinion, you're not serious," said Rep. Carolyn Maloney (D-N.Y.).

Rep. Eleanor Holmes Norton (D-D.C.) asked Horowitz point-blank if he found "any evidence that Attorney General Holder approved of the gun walking tactics that are under investigation."

"As we outlined in the report, we found no evidence that the attorney general was aware in 2010, before Senator Grassley's letter, of operation Fast and Furious and the tactics associated with it," Horowitz said.

"We found that the acting deputy attorney general was briefed about operation Fast and Furious in March of 2010, but we concluded, after looking at what that briefing involved, which was item 4 of a 7-item agenda in a 45-minute briefing, that it wasn't a sufficient briefing to put him on notice directly and expressly that gun walking was occurred -- had occurred," he added.

Horowitz clarified under questioning that his office never had to make any determinations about executive privilege, because they asked for all documents at the outset and received them.

"I think it's wonderful at one level that we have an independent entity like you to investigate," said Rep. Trey Gowdy (R-S.C.). "I just naively thought that's what the Department of Justice was."

Revisiting the issue of the documents withheld from Congress, Issa asked if Horowitz thought "it is appropriate for the department to deliberately withhold these documents without citing any reason or privilege for doing so."

"Let me just say, they were clearly, to us, highly relevant," the I.G. responded. "I frankly don't know the back and forth that occurred or the decision-making that occurred within the department, so I don't think I'm in a position to answer precisely that question."

"So when the attorney general has repeatedly said that he made unprecedented levels of documents available to us, he was thorough and complete, and he came before Congress so many times before February 4th and then omitted this, he omitted something which was clearly relevant and important to the investigation," Issa continued.

"As I said, I think the documents to us were highly relevant and important, which is why we spent so much time discussing them," Horowitz said.

"You all have painted the picture quite accurately for us. I don't think anybody up here likes the picture that we see," Cummings said. "To be frank with you, knowing Eric Holder the way I know him, the honorable man he is, I don't think he likes this picture."

Cummings and Issa agreed to bring the I.G. back in mid-January for an accountability review.

But another thing Horowitz couldn't answer is whether or not the U.S. was accountable to the Mexican government after sending guns over the border.

"Do you know when the Mexican government was informed about Fast and Furious? Or if they have been debriefed on it?" Gowdy asked. "Because I would imagine it could impact our relationship with law enforcement in Mexico."

"I don't know when they were debriefed and I don't know the extent to which they were debriefed about it," Horowitz said. "There were some indications in emails that we saw about the possibility of alerting the Mexican authorities, but I don't know."

"I look forward to the American people having an opportunity to read as much the material as can be made unsealed as possible," Issa said. "I believe the American people and the Terry family have an absolute right to have as much transparency as possible."