(CNN) -- The United States has "pretty good indications" that a man now held in Libya may have been involved in the deadly assault on the U.S. diplomatic compound in Benghazi, the chairman of the House Intelligence Committee said Sunday.
A U.S. official, speaking on condition of anonymity, told CNN last week that the FBI had been able to question a man identified by sources as Faraj al-Shibli. But it was still not clear what role, if any, al-Shibli may have played in the September 11 attack that killed U.S. Ambassador Christopher Stevens and three other Americans. A source briefed by Western intelligence officials said al-Shibli had recently returned to Libya from Pakistan.
"We're not sure yet," U.S. Rep. Mike Rogers, R-Michigan, told CNN's State of the Union. But. Rogers added, "we have pretty good indications that he is, at least, highly suspected of being involved."
Al-Shibli -- whose name also has been spelled "Chalabi" -- is the only known suspect in custody in connection with the Benghazi attack. 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 was released by a judge in January because of insufficient evidence.
The U.S. official said it was "advantageous" that al-Shibli was in Libyan custody, but there is not enough evidence to make an arrest at this point. Rogers told State of the Union that arresting al-Shibli could make it harder to question him.
"The problem with criminalizing this is that it lengthens the process. It slows everything down, and the key to these things is getting information soon," he said.
But the Intelligence Committee's ranking Democrat, Maryland Rep. C.A. "Dutch" Ruppersberger, said other jihadists charged with crimes in U.S. courts had continued cooperating even after being read their rights.
"We, as a nation, are the strongest country in the world," he told CNN. "And we need to show that we can try people and convict people in our country and protect witnesses and everything else. So, there are a lot of issues here, but it's got to depend on a case-by-case basis."