An Al Jazeera producer said his correspondents in Libya learned that rebels told Chris Jeon to leave the area. Jeon was last seen on a truck headed to Benghazi.
The 21-year-old math major, who has no military experience, told reporters that he went to Libya to offer his support to the rebels.
He bought a one-way ticket to Cairo and then made his way to the front lines of fighting in Libya.
Jeon's parents did not know their son had gone to Libya until journalists told them.