difficult, how? all bitcoin transactions are recorded in a blockchain ledger, so everything can still be checked again. but for washing, it can be bitcoin. because the mafia can put all the money into bitcoin, because bitcoin is very expensive and definitely will not take up much space in their wallet account.
The fluctuating bitcoin price keeps the corruptors afraid of saving money in bitcoin, so I'm not sure that the presence of bitcoin also leads to corruption, they are more comfortable saving money in overseas banks that are definitely safe and of greater interest.