Answer:
There is no such rule. Customers are placed on high risk lists due to perceived risks they pose to the bank, and are removed when the bank has determined that customer no longer presents such risk. You should review the FFIEC BSA exam manual, particularly the sections on risk assessment, customer due diligence, enhanced due diligence, and the expanded exam manual especially the section on persons and entities.
First published on BankersOnline.com 6/11/12