If the funds were sent to casinos, shouldn't the casinos have logs of what the money was used for?
Have you ever been to a casino? You buy chips with cash, then you play with the chips, then you cash the (remaining) chips in for cash. There is no tracking of where each chip came from. EDIT: Although maybe you're right, if the "gamblers" deposited funds to the casino via wire, direct from the fed, and then exchanged them for chips. So the casinos should presumably have some record of who came to claim that wire in…
Do you have evidence for this? I find it rather plausible that casinos have anti-fraud measures built into their chips to allow tracking of where each chip came from.
EDIT: A quick google shows this is indeed the case for some casinos at least: http://singularityhub.com/2011/02/12/1-5m-robbery-of-bellagi...