Sources are telling CNN that a suspect in the attack that killed Ambassador Stevens and 3 others has been captured in Libya.

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."