Technically it was an unregulated money transference service without KYC. The user that stole the cards from the bookstore was the one doing the money laundering part. I just enabled it (which is probably worse, legally).
I was investigated and cooperated fully.
Edit: I just remembered, the bank I used for the transference did do KYC for all users who were sent funds. This makes it more like "money dirtying", since the account is tied directly to a real identity.
Thanks for your detailed answer. Could you tell me what other things you had to deal with? Any prison, bad credit, fees, lawyer fees ?