I manage the Financial Investigative Unit for our FI, and when we identify unusual activity that we need more info on (e.g. source of cash/purpose of transactions), or the customer needs to be informed to cease his/her activity, we email the account manager to have him/her contact the customer. I've been asked to find out what the process is at other FI's. Are your customers contacted by your BSA Dept, the applicable account officer, or some other centralized department? Would greatly hearing your responses.
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