The new details about 24-year-old Sinh Vinh Ngo Nguyen were outlined in court documents.
Nguyen was waiting to board a bus to Mexico when he was arrested in Santa Ana last Friday.
He is accused of trying to join al Qaeda and lying on a U.S. passport application to aid international terrorism.
He has pleaded not guilty to the charges. The judge ordered he remain in custody on the grounds of danger and a flight risk.