This put an end to things for now...
A source with knowledge of the investigation told Fox News that authorities then found a backpack containing what they believed was five pounds of ammonium nitrate outside the vehicle -- however, while the substance was labeled "ammonium nitrate," field tests came back negative.
A notebook was also found at the scene and contained threatening phrases like "Al Qaeda" and "Taliban rule" and "defeated coalition forces," Fox News has learned.
Schlosser would not confirm reports that suspicious items have been found, saying the investigation is still ongoing.
"At this point we have someone who was suspicious by being in Arlington Cemetery overnight," he said. "I’m not sure if any devices have been found at this point."
The man arrested is a naturalized U.S. citizen who came to the country from Ethiopia, a source told MyFoxDC.com.
