Europol this week announced that 168 people were arrested in a massive operation that resulted in the identification of 1,504 money mules.

The European Money Mule Action ‘EMMA 4’, a global law enforcement action, took place over the course of three months, from September to November 2018. As a result, authorities in 30 states were able to identify 140 money mule organisers, Europol says.

The operation saw involvement from Europol, Eurojust, the European Banking Federation, and law enforcement from Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Greece, Germany, Hungary, Ireland, Italy, Latvia, Lithuania, Malta, Netherlands, Poland, Portugal, Romania, Slovenia, Spain, Sweden, Australia, Moldova, Norway, Switzerland, the United Kingdom and the United States.

As part of the money laundering crackdown, arrests were made in 20 states, in a coordinated effort to tackle the issue of ‘money mules’, who help criminals launder millions. The action enjoyed support from global and European banks.

EMMA 4, Europol reveals, resulted in the opening of 837 criminal investigations, many of which are still ongoing. Over 300 banks, 20 bank associations, and other financial institutions helped reporting 26,376 fraudulent money mule transactions, thus preventing a total loss of €36.1 million ($41.1 million).

Money mules are people who have been recruited by criminal organizations to hide the origin of ill-gotten money. Often tricked by the promise of easy money, these mules help cybercriminals transfer stolen funds between accounts and are usually offered a share of those funds.

Cybercriminals usually target newcomers to a country, or people who are unemployed or in economic distress. The authorities also noticed an increase in cases involving young people selected by money mule recruiters, with financially-distressed students increasingly targeted.

Authorities also noticed an increase in money-mule recruiting operations carried out via social media, via ads for fake jobs or get-rich-quick posts. Although the transfer of money from an account to another might take a single click, mules may face lengthy imprisonments and acquire a criminal record affecting the rest of their fives.

This week, a campaign to raise awareness of this type of fraud kicked off, to inform potential victims how they can protect themselves and what to do if they become a victim.

Also this week, a coordinated operation in 13 different countries resulted in the arrest of 235 suspects who bought counterfeit euro banknotes on illegal platforms on the Darknet.

Almost 300 house searches were conducted as part of the operation, 1 500 counterfeit euro banknotes seized, along with drugs, weapons (firearms, nunchaku, illegal knives and blades), computers, mobile phones, Bitcoins and hardware for mining virtual currencies.

“This joint effort highlights that complete anonymity on the internet and the Darknet doesn’t exist. When you engage in illegal activity online, be prepared to have police knocking on your door sooner or later,” Europol’s Deputy Executive Director of Operations, Wil van Gemert, said.

Related: Two Scammers, Five Mules Arrested in BEC Bust

Related: Europe Cracks Down on Money Mules: 178 Arrested in Global Operation