A secret cryptomining rig was found under the floors of a Polish court, stealing thousands of Polish Zlotys worth of energy per month (the equivalent of roughly $250 per 1,000 Zlotys). It’s currently unknown how long the rig was running because the illegal operation went undetected, partly because the computers used were connected to the Internet through their own modems rather than through the court’s network.

While no one has been charged yet with any crimes, the court seemingly has suspects. Within two weeks of finding the rig, the court terminated a contract with a company responsible for IT maintenance in the building, TVN24 reported. Before the contract ended, the company fired two employees that it said were responsible for maintenance in the parts of the building where the cryptomine was hidden. Poland’s top law enforcement officials, the Internal Security Agency, have been called in to investigate. The Warsaw District Prosecutor’s Office has hired IT experts to help determine exactly how much electricity was stolen from Poland’s Supreme Administrative Court in Warsaw, TVN24 reported.

The Supreme Administrative Court is the last resort for sensitive business and tax disputes, but no records seem to have been compromised. Judge Sylwester Marciniak — the chairman of the Judicial Information Department of the Supreme Administrative Court — told TVN24 that the discovery of the cryptomine “did not result in any threat to the security of data stored” in the court.