The chairman of a special House committee investigating the deadly 2012 attacks in Benghazi, Libya said Wednesday he is “keenly aware” that many people from both parties believe there is nothing left to investigate after a series of congressional and internal reviews, including a House report that found no wrongdoing by Obama administration appointees.

But Rep. Trey Gowdy, R-S.C., said that “some of those very same folks who now tell us to move on did not believe we should have investigated Benghazi in the first place.”

Speaking at the second public hearing of the Benghazi panel, Gowdy said the U.S. must learn from the past to prevent repeat incidents like the attack that killed the U.S. ambassador and three other Americans.

“We should not move on until there is a complete understanding of how the security environment described by our own government in court documents was allowed to exist,” Gowdy said. “We should not move on until there is a complete understanding of why requests for additional security were denied, by whom they were denied and why an ambassador trusted to represent us in a dangerous country was not trusted when he asked for more security.”

The 12-member Benghazi panel is reviewing efforts to secure U.S. diplomatic facilities and personnel as it continues investigating the Sept. 11, 2012 attacks that killed U.S. Ambassador Christopher Stevens, foreign service officer Sean Smith, and two CIA contractors, Tyrone S. Woods and Glen Doherty. A Libyan extremist, Ahmed Abu Khatalla, is facing trial on murder charges after he was captured in Libya and taken to the U.S.

House Republicans have called for spending up to $3.3 million on the select committee, created in May to investigate all elements of the assault and its aftermath. Multiple independent, bipartisan and GOP-led inquiries have faulted the State Department for inadequate security in Benghazi, leading to four demotions.

A report by the House Intelligence Committee last month found that the CIA and the military acted properly in responding to the 2012 attack.

Debunking a series of persistent allegations hinting at dark conspiracies, the investigation determined that there was no intelligence failure, no delay in sending a CIA rescue team, no missed opportunity for a military rescue, and no evidence the CIA was covertly shipping arms from Libya to Syria.

In the aftermath of the attacks, Republicans criticized the Obama administration and its then-secretary of state, Hillary Rodham Clinton, widely expected to run for president in 2016. People in and out of government have alleged that a CIA response team was ordered to “stand down” after the State Department compound came under attack, that a military rescue was nixed, that officials intentionally downplayed the role of al-Qaida figures in the attack, and that Stevens and the CIA were involved in a secret operation to spirit weapons out of Libya and into the hands of Syrian rebels. None of that is true, according to the House Intelligence Committee report.

The report found that the State Department facility where Stevens and Smith were killed was not well-protected, and that State Department security agents knew they could not defend it from a well-armed attack. Previous reports have found that requests for security improvements were not acted upon in Washington.

(AP)