As soon as that "tainted" banknote enters the banking system, you're fucked. They will freeze the money and the police will interrogate you where you got it from.
I have never heard of this happening before. Cashing into the bank is much rarer than cashing out, maybe that's why. Usually, you have more money in the bank than in cash.
Even if it happens, what do the police expect from me? Cash is untraceable. I have no damn clue where I sent or received a particular banknote. Any response I give to the source of the money cannot be verified.