Dutch and Europol authorities seized one of the largest bitcoin transaction mixers for money laundering. Such mixers combine transactions to 'launder' the currency which impedes determination of where it came from or to whom it is going.  

BestMixer.io handled $200 million in Bitcoin, Bitcoin Cash, Litecoin and other currencies. The investigation continues, which includes seeking those persons who used the service to process cryptocurrency obtained through criminal acts.  

Although this is the first seizure for these types of enterprises, it likely won't be the last. Such mixing sites will be under tight scrutiny by law enforcement, as they are a way for cybercriminals to effectively hide their ill-gotten-gains from activities such as ransomware and the hacking of cyrptocurrency exchanges.  

More details: https://www.hackread.com/crypto-tumbler-bestmixer-seized-for-money-laundering/