Can't they trace the money to the bank account? Find out who's bank account it is, etc?
Well I am not familiar with the details in this specific case, but judging by past scams I assume that they are using multiple bank accounts, and setting up other people in vulnerable groups (drug addicts, homeless people, etc.) to use their accounts for them. Then when you 'follow the money', you end up at the people that have been used by the scammers, and not the scammers themselves.