You can be convicted of "defrauding a bank of 'X' number of dollars" because you, e.g., overvalued some property which you had put up as collateral for a loan. Even if you paid back the loan in full and on time. Merely because someone later claims, "Hey, you overvalued the property you had put up as collateral for that loan, you dirty cheat!"
Just ask President Trump!
Regards,
Of course the financial institution did their due diligence and used comps etc to determine current values of the collateral, right?