Washington (CNN) -- A Republican lawmaker demanded Wednesday to know why investigators have not captured or killed any of the suspects in the attack on the U.S. diplomatic mission in Benghazi, pointing out that CNN was able to find a man who some say was the ringleader in the assault that left the ambassador and three other Americans dead.
Eight GOP lawmakers are asking that incoming FBI Director James Comey brief Congress within 30 days about the investigation. They say the administration's inquiry into the September 11, 2012, attacks in Libya has been "simply unacceptable," according to a draft letter obtained by CNN.
"One of the pertinent questions today is why we have not captured or killed the terrorist who committed these attacks?" Rep. Jason Chaffetz, R-Utah, told reporters. "News out today that CNN was able to go in and talk to one of the suspected terrorists, how come the military hasn't been able to get after them and capture or kill the people? How come the FBI isn't doing this and yet CNN is?"
Chaffetz was referring to CNN's recent interview with Ahmed Abu Khattala, who Libyan and U.S. officials have described as the Benghazi leader of the al Qaeda-affiliated militia group Ansar al-Sharia -- one of many groups that filled the vacuum of authority following the overthrow of Moammar Gadhafi.
He has been described as a "person of interest" in the investigation, according to officials.
In that interview, Khattala told CNN's Arwa Damon that he had not been contacted by any Libyan or American officials.
"Even the investigative team did not try to contact me," he told Damon, referring to the FBI.
When asked whether he would be willing to meet with investigators if they asked, Khattala said: "Yes, no problem. ...But not as an interrogation, as a conversation like the one we are having right now."
Damon spent two hours interviewing Khattala at a coffee shop at a well-known hotel in Benghazi, describing his demeanor as fairly relaxed. He allowed Damon to use an audio recorder to tape the conversation, but refused to appear on camera.
Khattala's narrative of the events that night was sometimes unclear and, at times, seemed to be contradictory, Damon said.
He admitted to being at the compound the night of the attack, but denied any involvement in the violence.
When he arrived at the perimeter of the compound, Khattala said he saw men carrying RPGs and medium guns, but that gunfire prevented him from getting close and entering the compound.
Khattala said by the time he managed to get inside the compound, everyone had withdrawn. He said he did not see any fires.
Asked about allegations he may have masterminded the attack, Khattala and two of the men he brought with him to the interview "burst out laughing," Damon said.
Khattala does not appear to be a man who is in hiding, having granted interviews to The New York Times, Reuters and other news agencies in the weeks following the Benghazi attack.
"Rumors continue to swirl about the whereabouts of suspects involved in the attack," the lawmakers wrote in their letter to Comey, who will replace Robert Mueller as FBI director in September.
"The FBI continues to add pictures of potential assailants to its website and asks the Libyan people to assist with identifying the alleged perpetrators. We struggle to understand why we don't know more about those who attacked two U.S. compounds and murdered four brave Americans. "
The FBI did not immediately respond to a CNN request for comment on the letter.
The letter was initiated by Chaffetz and Sen. Lindsey Graham of South Carolina, two of the fiercest critics of the administration's Benghazi response.
Others who agreed to sign the letter included Sens. John McCain of Arizona, Kelly Ayotte of New Hampshire and Ron Johnson of Wisconsin. On the House side, Darrell Issa, the chairman of the committee leading the House Benghazi investigation, Trey Gowdy of South Carolina and Jim Jordan of Ohio signed the letter.
In the letter, the lawmakers wrote: "We encourage you to be aggressive in your investigation to properly hold accountable those who attacked our compounds in Benghazi. We owe the families of those killed, and the people of this nation, answers to who was responsible and ensure they are held accountable."
The attack at the Benghazi diplomatic compound has become a political flashpoint in a long-running battle between the administration and Republicans, who accuse it of not bolstering security before the attack, of botching the response to it and of misleading the public for political gain less than two months before the November election.
The GOP suggests the administration removed specific terror references and stuck to an explanation advanced by U.N. Ambassador Susan Rice in television appearances -- later proved untrue -- that the attack was the result of a spontaneous demonstration over an anti-Muslim film that was produced in the United States.
The White House and its allies in Congress have said any confusion and conflicting information in the early hours and days after the assault stemmed from the "fog of war," not any deliberate effort to mislead the public.
CNN's John King reported from Washington and Chelsea J. Carter wrote from Atlanta.