U.S. Federal Marshals patrol outside the U.S. federal courthouse in Washington.

The Libyan militia leader accused of being part of the deadly 2012 attack on a U.S. diplomatic compound in Benghazi, Libya, has been “compliant but not cooperative” with U.S. interrogators, Representative Mike Rogers said on Sunday.

Ahmed Abu Khatallah, captured in Libya earlier this month by U.S. forces and held for nearly two weeks aboard a U.S. Navy vessel, was transferred to federal custody on Saturday. He appeared in U.S. District Court in Washington and, through a translator, pleaded not guilty to a terrorism charge in the attack that killed Christopher Stevens, the U.S. ambassador to Libya, and three other Americans.

Rogers, a Republican and chairman of the House Intelligence Committee, said on CNN’s “State of the Union” program that Khatallah was being held in the Washington, D.C., area after his arraignment.

“He’s being held in, I would argue, an appropriately secure environment given the nature of his crimes against the United States,” Rogers said. U.S. officials have not said where Khatallah is being held.

Khatallah was captured on June 15 by U.S. special operations forces and had been under interrogation since then on a Navy warship that brought him to the United States.

Rogers said the interrogation had not been especially fruitful. “He’s been compliant but not cooperative,” he said.

“You can imagine that he was not obstinate, he was not pushing back, but he was likely not providing information … not to the point where an FBI agent would say, ‘Hey, bingo, here we go. We’ve got something that would turn into actionable intelligence.'”

The Benghazi attack on Sept. 11, 2012, has been a long-running political issue, with Republicans contending the Obama administration initially misrepresented the circumstances and did too little to ensure the safety of U.S. personnel. Hillary Clinton, who was secretary of state at the time and is a potential presidential candidate in 2016, has been the focus of much of the criticism.

Khatallah denied in a Reuters interview in October 2012 that he was a leader of Ansar al-Sharia, an Islamist group Washington accuses of carrying out the assault on the consulate.

Rogers, echoing criticism by other Republicans since Khatallah’s capture, said it would have been preferable to treat him as an enemy combatant, hold him at the U.S. prison in Guantanamo Bay, Cuba, and put him before a military tribunal rather than try him as a criminal through the civilian justice system.

“If we’re going to do this for everybody engaged in terrorism around the world, we’d better start building prisons up by the dozens,” he said.

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