Europol has supported Spanish police* in an operation codenamed Walker, to take down a serious cybercriminal group during a coordinated action in Barcelona. With on-the-spot support from Europol, the action in Spain on 6 July resulted in the arrest of nine suspects, the dismantling of a sophisticated illegal call centre, six house searches and the seizure of numerous pieces of evidence; over 100 mobiles phones and stolen SIM cards, more than EUR 10 000 in cash, credit cards, computer equipment and other devices were taken away for further forensic examination.

The aim of this investigation was to target the cybercriminals and their accomplices who were involved in large scale telecommunication fraud as well as channelling and cashing-out the proceeds of their crimes. The criminals made fraudulent phone calls to premium service numbers set up and managed by other members of the criminal group based outside the EU. Each cybercriminal had their specialty and the group was involved in receiving mobile phones stolen from tourists in Spain, then harvesting and misusing the foreign mobile numbers (until they were blocked by the telecom operators in their countries), before then sending the money earned abroad.

Law enforcement analysed thousands of financial transactions to reconstruct the money flows and destinations across several jurisdictions. The criminal group relied on a network of accomplices who operated the destination bank accounts.

This was a very active criminal group and the damage caused by them is estimated to be at least EUR 2 million, affecting victims in various countries.

This international revenue share fraud (IRSF) is an insidious form of organised criminal activity that generates significant profits for the criminal groups and undermines the legal economy. The global estimated illegal income from this type of crime is more than EUR 45 million. Cooperation between law enforcement authorities, Europol and the telecommunication companies was crucial for the success of this operation, which represents a milestone in this specific area of digital crime.