In brief: When UK police conducted a raid of a suspected cannabis farm last week, they were surprised to find no marijuana. They found a farm, mind you, it was just of the digital variety. Crypto mining isn't illegal in the region, but stealing the electricity to power the operation is.

West Midlands Police said they had been tipped off that lots of people had been visiting the industrial unit in question. Upon closer inspection, they noted lots of wiring and ventilation ducts. Furthermore, police drones detected a considerable amount of heat coming from the top of the facility.

Police concluded it must be a marijuana growing operation, so they acquired a warrant and executed it on May 18.

Instead of drugs, they found a cryptocurrency mine. The people seen visiting at all hours of the day were likely just maintaining the hardware. The wiring, vents and heat? All par for the course when mining cryptocurrency.

It wasn't a total bust, however, as it was determined that the operators were stealing the electricity used to power the rigs.

"It's certainly not what we were expecting," said Sandwell Police Sergeant Jennifer Griffin. "My understanding is that mining for cryptocurrency is not itself illegal but clearly abstracting electricity from the mains supply to power it is."

Police seized the equipment and will be looking to take ownership of it through the Proceeds of Crime Act. No arrests have been made as the unit was unoccupied at the time of the raid but police are looking to get in contact with the facility's owner.