Europol and the Dutch Financial Criminal Investigative Service have seized the domain of a Bitcoin transaction mixing service.

Calling it the “first law enforcement action of its kind against such a cryptocurrency mixer service,” Europol said in a statement on Wednesday that the seizure of Bestmixer.io was the culmination of a year-long investigation that began last summer. As part of the move, police seized six servers based in Luxembourg and the Netherlands.

Europol has alleged that much of the money that passed through Bestmixer.io “had a criminal origin or destination” and that “the mixer was probably used to conceal and launder criminal flows of money”.

27,000 BTC in volume since May 2018

The law enforcement agency said that the service, which launched in May 2018, mixed approximately 27,000 BTC – over $200 million at today’s valuation.

Coin mixers – or “tumblers” – like Bestmixer.io work by pooling funds together and creating a web of new transactions in an effort to obfuscate their original source. Typically, users pay a fee on top of the funds they send in, receiving their money back from a wholly new address.

Europol’s statement suggests that the investigation isn’t complete and that authorities intend to follow up on the information gleaned from this week’s server seizures.

“The Dutch FIOD has gathered information on all the interactions on this platform in the past year. This includes IP addresses, transaction details, Bitcoin addresses, and chat messages,” the agency said.

“This information will now be analysed by the FIOD in cooperation with Europol and intelligence packages will be shared with other countries.”

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