Police in the UK executed a drugs warrant this month on an industrial unit expecting to find a cannabis farm - but instead found a cryptocurrency mine.
The officers forced entry to the unit in the West Midlands after intelligence had identified lots of people visiting at different times of the day and a drone picked up a considerable heat source.
Those are classic signs of an illegal cannabis factory, according to the police, but instead it turned out to be 100 computers mining bitcoin, stealing thousands of pounds worth of electricity.
Police took the computers and are looking to permanently seize them under the Proceeds of Crime Act, said Sandwell Police Sergeant Jennifer Griffin, but didn't find anyone on the premises.
"My understanding is that mining for cryptocurrency is not itself illegal but clearly abstracting electricity from the mains supply to power it is," said Sgt Griffin.
"It's certainly not what we were expecting! It had all the hallmarks of a cannabis cultivation set-up and I believe it's only the second such crypto mine we've encountered in the West Midlands."
Earlier this month Tesla CEO Elon Musk announced the electric car company was suspending the ability to buy cars using bitcoin due to environmental concerns, despite the company purchasing $1.5 billion worth in early 2021.
In a statement posted on Twitter, Musk said the company was "concerned about rapidly increasing use of fossil fuels for Bitcoin mining and transactions, especially coal, which has the worst emissions of any fuel".
Bitcoin currently consumes around 110 Terawatt Hours per year, which works out at around 0.55 percent of global electricity production, according to the Cambridge Centre for Alternative Finance.
That's roughly equivalent to the total power of a small country like Sweden or Malaysia.
Musk remains supportive of cryptocurrency, and particularly the meme-based dogecoin. His public musings, including an appearance of television show Saturday Night Live, have impacted on the price of cryptocurrencies.