(CNN) -- A man suspected of involvement in the September attack on the U.S. diplomatic compound in Benghazi is being held in Libya, according to two sources who have spoken with CNN.
Both sources confirmed the man's name as Faraj al-Shibli (also spelled Chalabi). One of the sources, who has been briefed on the arrest by Western intelligence officials, said al-Shibli was detained within the past two days and had recently returned from a trip to Pakistan.
A Libyan source also confirmed that al-Shibli was in custody in the north African nation. The FBI was given direct access to him, and it interviewed him recently in the presence of Libyan authorities, according to the Libyan source.
The Libyan government allowed one or more members of the U.S. law enforcement agency to question the man -- something that is not necessarily done when a person is detained in a foreign country -- around the time on Wednesday when its prime minister, Ali Zeidan, met with U.S. President Barack Obama.
The United States has been pressing Libyan authorities on the Benghazi investigation, with FBI Director Robert Mueller traveling to Tripoli in January for talks on the case.
It is unclear exactly what al-Shibli's role might have been or whether he was present at the U.S. compound at the time of the attack. It's also unclear whether his detention is likely to lead to charges in connection with the assault on the compound, which resulted in the deaths of four Americans, including U.S. Ambassador to Libya Chris Stevens.
Rep. Jason Chaffetz, a Utah Republican and a member of the House Homeland Security Committee, said Thursday that "we think there are more than a dozen people involved in this."
"The idea that potentially we have somebody ... it's obviously positive news," Chaffetz told CNN. "... This is the most positive development I've seen in the past six months."
Al-Shibli is the only known suspect in custody in connection with the attack in Benghazi. A 26-year-old Tunisian, Ali Ani al Harzi, was held in Tunis for several weeks in connection with the assault on the compound after being extradited from Turkey. But he was released by a Tunisian judge in January on grounds on insufficient evidence.
And in December, a U.S. official with direct knowledge of the investigation said authorities were examining whether the alleged leader of a post-revolution terrorist network in Egypt had played a role in the September 11 attack. Mohammed Jamal Abu Ahmed was released from jail after the downfall of Egyptian President Hosni Mubarak and is believed to be the driving force behind a new militant group, according to two U.S. officials.
He is currently reported to be in prison in Egypt after being arrested in December, when police raided an apartment allegedly being used by a jihadist group active in Cairo. An associate of Abu Ahmed's subsequently said that he had not been in Benghazi or anywhere in Libya on the day of the attack on the compound.
Al-Shibli comes from a town called Sidi Armouma al-Marj, about 50 miles (80 kilometers) from Benghazi. He was a member of the Libyan Islamist Fighting Group, a militant organization that tried to overthrow the Gadhafi regime in the mid-1990s.
In 2004, the Libyan government reported al-Shibli to the United Nations as on its "wanted" list and issued an Interpol "Red Notice" seeking his arrest.
It was the second warrant issued by the Gadhafi regime for al-Shibli's arrest. In 1998, he was named with two other Libyans as allegedly involved in the murder of a German counterintelligence official, Silvan Becker, and his wife, Vera, who were killed in the Libyan town of Sirte in 1994. The Libyan authorities also issued an arrest warrant for Osama bin Laden in connection with the crime.
Investigators have learned that he has had contact with the Yemen-based al Qaeda in the Arabian Peninsula and al Qaeda members in Pakistan, sources said.
However, some analysts have cast doubt on the Gadhafi regime's assertion that Libyan Islamist Fighting Group members carried out the attack on the German couple.
Jihadist groups are strong to this day between Benghazi and the town of Derna to the east, an area that includes al-Marj. Several groups are thought to have camps in the Green Mountains between al-Marj and towns along the coast.
U.S. investigators have identified at least 15 individuals whom "we're taking a serious look at," a U.S. law enforcement official said in January, indicating that some of them were identified on video of the assault. Ultimately, the official said at the time, "we will get indictments, but it's not possible to put a timetable on it."
CNN's Fran Townsend, Ross Levitt, Carol Cratty and Jim Acosta contributed to this report.