Updated

Kevin Ohlson served as Attorney General Eric Holder's chief of staff from January 2009 to January this year, but he says he knew nothing about so-called gun-walking operations that were going on during that time through the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Ohlson appeared Thursday before the Senate Armed Services Committee because he's been nominated by President Obama to become a federal judge on the United States Court of Appeals for the Armed Services. That gave Sen. John McCain, R-Ariz., the opportunity to ask Ohlson some very pointed questions about what he knew about Operation Fast and Furious and when.

Prior to the hearing, McCain sent a detailed letter to Ohlson calling on him to divulge any and all connections he may have had to Fast and Furious. The botched anti-gunrunning program allowed so-called straw buyers to purchase guns with the goal of tracking them to the traffickers. But investigators lost track of many of the guns, as they wound up in the hands of cartels and in some cases at the scenes of violent crimes.

"You were 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," McCain wrote. In his written response, Ohlson stated that he "had no knowledge of, provided no advice about, and had no involvement in Operation Fast and Furious."

It was a position Ohlson maintained Thursday before the committee, despite McCain's apparent skepticism.

McCain repeatedly asked Ohlson about the death of Border Patrol Agent Brian Terry and why Ohlson didn't push for answers about what happened.

"When a border patrol agent is murdered, you don't say, 'Hey, what's the story here; how did this happen?'"

Ohlson said he was briefed on Terry's death but didn't link it to Operation Fast and Furious because he had no knowledge of the gun-walking program at that time.

However, Ohlson acknowledged both in his written response and in his testimony before the committee that he had received briefing memos that referenced Fast and Furious.

"I have been informed that routine courtesy copies of weekly reports were forwarded to me that referred to the operation by name. ... I did not review them," Ohlson wrote.

On Thursday, McCain asked Ohlson about a specific memo that he received discussing the Operation: "So, you get a memo and it says it's part of Operation Fast and Furious and you don't say, 'Hey, what's Operation Fast and Furious?'"

"I did not read that report," Ohlson responded.

Ohlson acknowledged that he served as a "funnel" or gatekeeper for all the memos and information that came to the attorney general's office and to Holder. Ohlson said that he first learned about Fast and Furious through press accounts in February of this year, after he had left his position within the Department of Justice.