Wondering if this scenario warrants a SAR filing? Amount is less than $5000.00 loss.
Customer stated she had her purse stolen. A few days later checks were presented for partial deposit partial cash back. The 'stolen' ID was presented for verification. Now the checks have been returned as fraudulent. We are unable to determine if the customer is the victim or the fraudster. Local police have been contacted and are performing their investigation.

What about the total of the fraudulent checks though--not just the loss. Was it over $5K? If so, and you think your customer might be the fraudster, I would file.

In all likelihood, your customer is probably a victim. You're describing textbook Felony Lane Gang activity.

Consider filing, even below threshold, if there is information about the checks used, etc. that could be valuable to a multi-bank multi-state investigation.

But more importantly, connect with the drawee bank and with other local banks in your area that have experienced similar fraud (if it happened to you, it is also happening to your neighbors). Make sure everyone is reporting this activity as it happens, and make sure the locals are made aware of each others' cases.