A loophole meant cryptocurrencies that didn't belong to them could be stolen — and detectives later uncovered bundles of cash and gold bars, as well as luxury watches.
Four Britons have been jailed after being convicted of a £21m ($26m) crypto fraud.
The Crown Prosecution Service says they had fraudulently obtained and laundered Bitcoin — as well as other digital assets — from a crypto exchange based in Australia.
Stephen William Boys, Kelly Caton, Jordan Kane Robinson and James Austin-Beddoes have been sentenced to a total of 15 years behind bars.
Officials say they all had ties to a man called James Parker, "who masterminded the conspiracy" from his home in the North of England.
Between October 2017 and January 2018, he had uncovered a loophole that allowed them all to "dishonestly obtain credits" worth millions of pounds at the time.
From here, they withdrew the cryptocurrency from their trading account — and laundered the funds through a series of online accounts to cover their tracks.
Officials say Parker died before criminal charges could be brought — but almost £1m ($1.22m) has been recovered and is now being returned to the Australian exchange.
Pictures shared online showed bundles of cash and gold bars that were derived from this fraud, as well as a series of luxury watches.
Jonathan Kelleher, who works with the Crown Prosecution Service, said:
"These offenders used the internet from the comfort of their own homes to obtain tens of millions of pounds worth of Bitcoin which did not belong to them. Cyber-enabled crime presents an increasing threat to international economic stability, as well as to honest individual investors in cryptocurrency."
Meanwhile, Detective Superintendent David Wainwright from Lancashire Police said:
"This was a large and complex case in which these offenders have now been brought to justice."
