A federal jury in Washington on Tuesday convicted a Libyan man of terrorism in the attack on the U.S. Consulate in Benghazi, but acquitted him of the most serious charge, murder.
The 2012 attack killed four people, including U.S. Ambassador to Libya Christopher Stevens.
U.S. commandos captured Ahmed Abu Khattala in 2014 and brought him to the United States for interrogation and trial.
His attorneys argued the evidence against him was shaky. They also said questioning him about the attack before advising him of his rights under U.S. law was illegal.
While prosecutors convinced the jury that Khattala led the militant group that attacked the consulate, they failed to prove he was directly responsible for the deaths of Stevens and the others.
But Khattala will still most likely spend decades in federal prison after he is sentenced.
Another suspect, Mustafa al-Imam, was captured last month and also faces trial.