A man suspected of robbing a southwestern Illinois bank is jailed pending charges, as authorities try to figure out whether he may have been involved in holdups in other states.  Investigators say the man was arrested yesterday near a Swansea cornfield after they found a car matching the description of a vehicle that had been used two hours earlier to rob the Bank of O’Fallon.  The search for the man involved dozens of law enforcers and an Illinois State Police airplane.  Authorities say the man entered the bank, implied he had a weapon and demanded money from a teller before running away.  O’Fallon interim police chief Jeff Wild says the man may be responsible for other bank robberies outside Illinois.  There’s no immediate word on charges and the FBI is investigating.