Officials at Poland’s Supreme Administrative Court in Warsaw discovered a number of high-powered cryptocurrency mining rigs hidden in the courthouse — including in a ventilation duct and beneath a raised floor — which had been powered by electricity from the court’s mains supply.

The devices had their own modems to connect to the internet, according to Polish news channel TVN 24, meaning they were not connected to the court building’s network.

Judge Sylwester Marciniak told the broadcaster that the episode “did not result in any threat to the security of data stored in the Supreme Administrative Court,” and added that Poland’s Internal Security Agency — the country’s FBI — had been informed.

According to TVN 24, the devices were capable of consuming several thousands Polish Zlotys of energy per month — with 1,000 Zloty worth about $250 — and had been placed near power supply equipment.

A few weeks after they were discovered in September, the president of the court terminated its contract with an external company that had been hired to maintain the building’s devices.

TVN 24 reported that it had dismissed two employees who were responsible for servicing the part of the building where the crypto mining equipment had been ensconced.

The equipment has since been dismantled and seized by police and an investigation into the incident is being led by the district prosecutor’s office regarding the theft of electricity. To date, no one has been charged.

It is not the first time that a building of justice has unwittingly played host to cyber misdeeds.

Back in 2015, five prisoners in Ohio were caught after having reconstructed two personal computers from parts they had been breaking down for recycling.

These computers were hidden behind a plywood board in the ceiling of a closet and then connected to the Ohio Department of Rehabilitation and Corrections network.

After hacking into the network using dodgy login credentials, they used their access to issue passes for inmates to move around the facility, and in one instance even stole another inmate’s personal information to successfully apply for several credit cards.