If the police contact the bank that they have an investigation on our customer for bank fraud, do we file a SAR? Obviously the police already know about the guy but I still think we should file.

You should review the customer's activity to see if you think a SAR is warranted. You would not file a SAR based strictly on the police contact.

he has used a false SSN, so that should prompt the SAR correct?

I would file for that reason.

If a customer has provided you with false information, your first priority should be in closing the account. SAR filing is a secondary issue at best.

Form 111 places enough emphasis on documentation to make it clear that a filing is required if the appropriate dollar threshold is met; i.e. whether you are you sure of enough information to name a suspect.

Law enforcement's previous knowledge of a situation is irrelevant to whether you file a SAR.

the account is closed and everything else has been dealt with. I was mainly checking on "Law enforcement's previous knowledge of a situation is irrelevant to whether you file a SAR"

Thanks to all