Answer:
If the dollar amount of those checks aggregates to more than $5,000, I'd definitely file a SAR for bank fraud.
If you have been able to charge those checks back to the account successfully, you'll want to watch carefully for others coming back. I do suggest closing the account, but holding off on sending out a check for the balance until you're reasonably sure you're covered by the midnight deadline for any future returns.
If you sustain a loss, contact bank counsel about the feasibility of filing charges. It might not be worth the cost to do so.
First published on BankersOnline.com 10/31/11