European investigators say it involved the Russian mafia, criminal cells, off-shore shell companies and even a third-tier Portuguese soccer team.
And it culminated in the detention of Alexander Tolstikov, a Russian businessman and the owner of the third-tier team, Uniao de Leiria, a Portuguese official told CNN.
Tolstikov was detained on suspicion of tax fraud, criminal association, money laundering, corruption and forgery of documents, according to Antonio Sintra, head of the Leiria Department of Criminal Investigation of the Portuguese Police.
Sintra said one of the club's administrators and its financial director were also detained. The three suspects are expected to be arraigned in court within the next 48 hours.
Criminal gang linked to crimes in six other European countries
Europol, the European law enforcement agency, said Wednesday
that the three people detained were part of an important cell of a Russian mafia group that has laundered several million euros across multiple European Union countries since 2008.
The group has "links with serious and organized crimes committed in Austria, Estonia, Germany, Latvia, Moldova and the United Kingdom," Europol said in a news release.
Reached by CNN, a representative of the club declined comment.
The suspects were arrested after more than 70 Portuguese police officers searched 22 locations in the Lisbon, Leiria, Braga and Viseu areas of the country, along with Uniao de Leira's and SC Braga's football stadiums and the offices of the two top-tier Lisbon rivals, Benfica and Sporting. Also searched were private homes, companies, vehicles, accounting offices and a law firm, the Portuguese Prosecutor's office said in a statement.
Several thousand euros in cash, mostly in 500-euro bills, were also seized, Europol said.
Sintra said Benfica, Sporting and Braga were "not under investigation." He said searches were carried out at the three clubs' offices because they acquired Russian players from Leiria and had documents that could help the investigation.
'Front men for opaque and sophisticated networks'
Uniao de Leiria, once a top-tier football team and coached at one point by noted Portuguese manager Jose Mourinho, was relegated to Portugal's lower divisions after facing financial difficulties in 2012.
Leiria's money woes made it a prime target for the criminal network, which, according to Europol, targeted "EU football clubs in financial distress." The network infiltrated these clubs by providing much-needed short-term donations or investments, eventually orchestrating their purchase, Europol said.
Europol said the Russian network used "front men for opaque and sophisticated networks of holding companies invariably owned by shell companies registered offshore and in tax havens," allowing the real owners to remain unidentified.
"Once clubs are under the control of the Russian mafia, the large scope of financial transactions, cross-border money flows, and shortcomings in governance allow clubs to be used to launder dirty money well as for betting activities," Europol said.
The investigation by Portuguese and European law enforcement officials started more than a year ago, after Leiria was acquired by Tolstikov in 2014.
According to Europol, suspicion was aroused by the "high standards of living that the suspects enjoyed" while in Portugal. The suspects imported "large amounts of money from Russia to Portugal," in violation of EU law, Europol said.