Putting a sharper edge on the "source of funds" issue, sometimes the choice comes down to flatly asking the customer where the money came from or filing a SAR. Personally, I would prefer to ask the question.
While SARs are oftentimes filed because the bank simply cannot figure out what's going on, the customer always knows what's going on. Asking him is just the simplest thing to do and the world doesn't need any more worthless SARs.
It's a difficult task for anyone and not one easily imposed on a 19 year old CSR. It can be done by an officer. It can be done after the fact. It can be done casually. It can be done...
If the customer refuses to explain then I've got another sentence for the SAR that I was already stuck with filing. Unfortunately, I've also got another customer for the "watch" list.
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.