A collaboration between Europol, the Spanish Civil Guarda, Finnish authorities, and the U.S. Department of Homeland Security, operation "Tulipan Blanca" resulted in 11 arrests and investigations in to 137 individuals. Crime ring members laundered funds sourced from other crime groups, who made their money selling drugs, by utilizing cryptocurrency and credit cards.
Per a press release by Europol posted on April 2 2018, drug traffickers contacted criminal parties in Spain to get them to launder money for them, picking up illicit proceeds in the form of cash which was split in to smaller amounts, deposited in to hundreds of bank accounts.
Criminals acquired credit cards which were tied to these bank accounts, traveled to Colombia, and withdrew cash at institutions. After realizing that cash withdrawal activity was inherently suspicious, they changed their methods to include cryptocurrency.
A local Finnish bitcoin exchange was used by the criminals to convert the cash into bitcoins, further changing bitcoins to Columbian pesos, then deposited in to Columbian bank accounts, all in the same day.
The investigation resulted in the discovery of more than EUR 8 million in cash spread out across at leas 174 bank accounts.
https://www.europol.europa.eu/newsroom/news/illegal-network-used-cryptocurrencies-and-credit-cards-to-launder-more-eur-8-million-drug-trafficking