The Bulgarian Special Prosecutor’s Office is involved in a wide-ranging, international investigation into companies and persons behind the digital currency investment scheme OneCoin, which has been widely accused of constituting a pyramid scheme.

In a Jan. 19 statement, the office said that it was collaborating with officials in Germany as well as those from international groups Eurojust and Europol to investigate OneCoin. Germany has been conducting an investigation into OneCoin since as early as last year, a move that came after it effectively banned OneCoin and its promoters from the country.

The Bulgarian prosecutor’s office said that, in the past two days, corporate offices tied to a company connected to OneCoin were raided. Dozens of witnesses have also been interviewed, according to the government.

The statement explained:

“On 17 and 18 January 2017, in the presence of representatives of Europol and the German investigative bodies, the offices of Wan Network Services and 14 other companies were searched. A lot of material evidence has been seized, including servers, so far, 50 witnesses have been questioned.”

The statement also highlighted the international nature of the investigation, pointing to a number of countries that have launched inquiries of their own in recent months. In July, for example, reports indicated that OneCoin founder Ruja Ignatova was being charged by Indian authorities in connection with the alleged pyramid scheme.

“At present, companies associated with OneCoin Ltd. are being investigated in England, Ireland, Italy, the United States, Canada, Ukraine, Lithuania, Latvia, Estonia and many other countries,” the prosecutor’s office said.

Editor’s Note: Some of the statements in this report have been translated from Bulgarian.