Updated

The leaders of the State Department's internal review of the Benghazi terror attack were grilled Thursday by congressional Republicans who suggested their probe amounted to an "inside job" that let senior officials off the hook.

The hearing before the House Oversight and Government Reform Committee comes days after the committee released a draft report alleging that top State Department officials escaped blame for some of the policy decisions that left the U.S. compound in Benghazi less secure. The leaders of the internal review board -- former Amb. Thomas Pickering and former Chairman of the Joint Chiefs of Staff. Gen. Mike Mullen -- were called to testify, and defended the board's objectivity and findings.

"I had no sense anywhere that there was any conflict of interest," Pickering said. "I'm proud of the report."

Four mid-level employees were disciplined in the wake of the report, though most were later re-assigned. More than a year after the Sept. 11, 2012, attack in which four Americans were killed, many Republican lawmakers say there still hasn't been any measurable accountability.  Their scrutiny recently has turned to the work of the Accountability Review Board, led by Mullen and Pickering.

"It looks like ... sort of an inside job of an investigation. The Department of State looking at the Department of State," Rep. John Mica, R-Fla., said.

Pickering later explained that the principle goal of the review was to find out what went wrong so such a tragedy does not happen again.

"This was not, quote, a gotcha investigative panel," he said.

Rep. Darrell Issa, R-Calif., retorted: "Obviously this was not a gotcha panel. Because nobody was gotcha'd."

The hearing was one of three being held on Benghazi on the House side this week. Democrats complained that Republicans are re-treading over tired talking points, and that the new attempt to pick apart the State Department review is inappropriate.

Rep. Elijah Cummings, D-Md., top Democrat on the committee, said accusations that the review was a whitewash are "reckless."

"Those kinds of statements upset me, because I think that they are so unfair, and we're better than that," Cummings said. "This Benghazi review was one of the most comprehensive ARB reviews ever conducted."

Though it has been a year since the attack, lawmakers' frustration stems in part from the fact that nobody has been brought to justice in connection with the attack. On top of that, Secretary of State John Kerry recently re-assigned most of those who were disciplined internally over the security posture at the Benghazi post.

In a heated exchange, Rep. Jim Jordan, R-Ohio, also suggested Mullen was not acting independently when he gave Cheryl Mills, a top aide to former Secretary of State Hillary Clinton, a heads-up that department official Charlene Lamb might not be an ideal witness at a House hearing last fall. Mullen acknowledged that he told Mills he didn't think Lamb would "represent the department well."

Jordan questioned how that intervention squared with his claims that the review board was independent.

Mullen and Pickering claimed it was part of the board's obligation to give status updates to the secretary of State through her staff.