To quote host:
To date, we have not been able to determine the origin of the money used for the 9/11 attacks.
http://www.9-11commission.gov/report/911Report_Exec.htm
FBI Director Mueller said, "The hijackers also left no paper trail. In our investigation, we have not uncovered a single piece of paper – either here in the U.S. or in the treasure trove of information that has turned up in Afghanistan and elsewhere – that mentioned any aspect of the September 11th plot"
http://www.fbi.gov/pressrel/speeches/speech041902.htm