Awais Younis, 25, of Arlington, a native of Afghanistan, was arrested in November after an acquaintance contacted the FBI. The acquaintance was alarmed by comments made by Younis during a Facebook chat about building pipe bombs with specific types of shrapnel to cause maximum damage on the Metro system.
The indictment for interstate communication of a threat was handed up Wednesday in U.S. District Court in Alexandria.
A magistrate judge earlier ordered Younis be held pending trial. The judge also ordered that Younis receive a mental health evaluation.