Italian police on Monday arrested 25 Eritreans, 12 Ethiopians and an Italian who they said belonged to an organization that had smuggled thousands of migrants into Europe from Africa.

The arrests were made in ten cities across Italy, Sicilian police said, and the suspects were accused of people smuggling, drug trafficking and various financial crimes in a swoop made possible by the testimony of an Eritrean man arrested in 2014.

The man had “for the first time in Italy, given a complete reconstruction of the criminal activity of one of the most ruthless international migrant-trafficking bands, operating in North Africa and in Italy,” a police statement said.

His testimony allowed the police to raid a small perfume shop in central Rome on June 13, where they seized 526,000 euros ($585,000) and $25,000 in cash, as well as an address book containing information on the members of the ring, it said.

Europe’s worst migration crisis since World War Two has seen hundreds of thousands of people pay smugglers to make the trip to Europe from Libya in often unseaworthy boats and dinghies.

Italy has borne much of the brunt, with about 60,000 migrants arriving by boat on its shores this year.