The Dutch Fiscal Information and Investigation Service in cooperation with Europol and Luxembourg authorities have seized and closed down Bestmixer.io, a large cryptocurrency mixing service. According to a post by Europol, the investigation into Bestmixer.io took place in mid-2018, with Internet security company, McAfee, supporting the effort.

According to Europol, Bestmixer.io was one of the three largest cryptocurrency mixing services, offering its services for bitcoins, bitcoin cash, and litecoins. The service was started in May 2018 and has mixed at least $200 million worth of cryptocurrencies over that time.

Cryptocurrency mixing services typically work by leveraging the CoinJoin protocol to pool together multiple different funds to obfuscate the trail of certain transactions. Bestmixer.io, however, provided a centralized, custodial mixing service. Europol states that "the investigation so far into this case has shown that many of the mixed cryptocurrencies on Bestmixer.io had a criminal origin or destination" and that "the mixer was probably used to conceal and launder criminal flows of money."