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The confirmation of a former aide to Attorney General Eric Holder to the U.S. Court of Appeals for the Armed Forces may be in peril over his response to questions posed by Arizona Sen. John McCain about his knowledge of Operation Fast and Furious.

Kevin Ohlson, who worked as Holder's chief of staff from January 2009 to January 2011, faces a confirmation hearing on Thursday for the post. The panel with jurisdiction is the Senate Armed Services Committee, of which McCain is the ranking Republican and Sen. Carl Levin, D-Mich., is chairman.

In his response Monday to a questionnaire sent from McCain last week, both obtained by Fox News, Ohlson said he knew nothing about the operation while he was at the Justice Department.

"During my tenure as chief of staff and counselor to the attorney general, I took no actions in regard to, had no knowledge of, provided no advice about, and had no involvement in Operation Fast and Furious," he wrote. Ohlson wrote he did participate in a prep session with Holder on Fast and Furious earlier this month before Holder testified to Congress.

In the letter sent by McCain, he wrote that as Holder's chief of staff Ohlson was "in a position to be informed about the Operation, to make decisions regarding the operation, and to know what information about it was and was not provided to the attorney general."

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    But in his response, Ohlson wrote he had "been informed that routine courtesy copies of weekly reports were forwarded to me that referred to the operation by name, but that did not provide any operational details and did not refer to gun walking or anything similar."

    But Ohlson said nothing on the cover sheets of the reports indicated they contained important or sensitive materials and he didn't review them.

    The latest response highlights a recurring theme coming from the Department of Justice about Fast and Furious that has raised troubling concerns for Republicans, specifically, that officials there did not get into details or make the effort to look further into the botched gun-walking program.

    Fast and Furious was run out of the Department of Alcohol, Tobacco, Firearms and Explosives and aimed to allow straw purchasers illegally buy guns from U.S. shops in order to trace where they went. Hundreds of those guns disappeared into Mexico, and the operation blew up in late 2010 after the murder of U.S. Border Agent Brian Terry. Two guns linked to the operation were found at the crime scene.

    But in response to questions raised about the program, Holder said memos about Fast and Furious addressed to him were never brought to his attention. Holder's then No. 2, Gary Grindler, did receive a briefing on Fast and Furious, but didn't discuss it with others, he says, because the tactics were never mentioned.

    Head of the Justice Department's Criminal Division Lanny Breuer said he knew of a different gun-walking case but didn't ask if others were occurring. Breuer's deputies also approved wiretaps in Fast and Furious, but only looked at cover sheets, according to Justice Department officials.

    Lower-level attorneys from the department's Gang Unit briefly worked on Fast and Furious as well as other gun-walking cases, but their work never filtered up.

    Ohlson left Holder's office in January 2011 to become chief of the Professional Misconduct Review Unit. He said that there was no linkage between his move and Terry's death.

    House Oversight and Government Reform Chairman Darrell Issa said the whole case shows that changes are needed at the Justice Department.

    Holder "wouldn't even admit that, in fact, Fast and Furious led directly to the death of Brian Terry. He seems to want to obfuscate that," Issa, R-Calif., told Fox News on Tuesday, not referring to Ohlson's replies to the questionnaire.

    "That shows that we really need to get some kind of change at the Department of Justice in the AG's office, or we're not going to get the kind of change Americans can believe in."

    Fox News' Trish Turner contributed to this report.