Ahmed Abu Khatallah remains under a watchful eye.<br/> <br />The Libyan militant is an alleged mastermind in the 2012 Benghazi attack on a U.S. diplomatic compound.<br/> <br />And for the second time after being captured on June 15, Khatallah left a Washington DC federal court under tight security.<br/> <br />He faces criminal charges for the attack that killed four Americans.<br/> <br />On Saturday, Khatallah pleaded "not guilty" to a terrorism conspiracy charge.<br/> <br />And on Wednesday, his attorney said prosecutors had yet to provide any evidence of Khatallah's involvement in the attacks.<br/> <br />It's not immediately clear when his trial would start.<br/> <br />But a judge has ordered him to remain in U.S. custody as he awaits it.
