The best way to legally launder money is to use a casino. You bring in your dirty money, exchange it for chips. Then sit on your chips for a week, maybe a month, then go back and cash out your chips for clean money.
Meanwhile, all the cash you moved through the casino is now scattered to some 50-100 different banks as it gets deposited in their daily drops and then transferred as necessary between the banks. In a few weeks, the dirty money is albeit untraceable.
You showed up with lets say $50k at the casino, you departed with the same $50k. If you'll be investigated, you still can't justify the money you walked in with.
Criminal 1 buys $50k in chips using wired funds. Gives chips to criminal accomplices 2, 3 and 4.
CA2, CA3 and CA4 come into the casino a few different times over several months, gamble for while for a net zero gain or loss, and then convert their "winnings" from chips into cash in chunks of $5k or so - flying under the radar.
C1 never needs to come back to the casino where the police might catch him - and he is the only one who is linked to the big heist.
The large value chips have rfid tags in them. You would be investigated. You'd need to play some game with a slight loss to the casino to swap them out.
The best way to legally launder money is to use a casino. You bring in your dirty money, exchange it for chips. Then sit on your chips for a week, maybe a month, then go back and cash out your chips for clean money.
Meanwhile, all the cash you moved through the casino is now scattered to some 50-100 different banks as it gets deposited in their daily drops and then transferred as necessary between the banks. In a few weeks, the dirty money is albeit untraceable.