Lichtenstein and Morgan are charged with conspiracy to commit money laundering
If so, this means that (outside tax obligations) they may have gotten away with it essentially by sitting on the money doing nothing for 5 years and then openly transferred it to themselves. Since they took actions that were meant to launder the money, they opened themselves up to the money laundering charges on their own.
https://www.law.cornell.edu/uscode/text/18/3282
This is similar to many financial regulations where you can have completely legally obtained money but if you deposit $9,000 followed by depositing $1,000 thereby avoiding a CTR notification to the government required for a $10,000 deposit, you're guilty of "structuring" your deposits.
https://www.fincen.gov/sites/default/files/shared/CTRPamphle...