[lurked_for_a_decade]

The serial numbers of every dollar going in and out of a financail institution is tracked. That is all I will say.

[Svartalfiar]

The serial numbers of every dollar going in and out of a financail institution is tracked. That is all I will say.

So they know which banks handed out the bills, and which banks had them deposited. They still don't know by whom or what happened with the bills in the intermediary timeframe.