The second-largest bitcoin theft culminated in February with the arrests in New York of 34-year-old Ilya Lichtenstein and 31-year-old Heather Morgan. Their arrest lifts the veil on certain sophisticated techniques used by criminal organizations and other high street fraudsters.

Totaling $5.7 billion worth of bitcoins, the cryptocurrency amassed in a digital wallet found at the couple's home represents no more and no less than the largest financial seizure ever made in the United States (and probably the world). What the investigation reveals most interesting, in addition to the inconceivable sums for ordinary mortals, is how criminals who launder cryptocurrencies go about camouflaging their illicit origins and transforming them into money.

The whistleblower is a far more complex operation than simply running a currency exchange office, as the Montreal mafia did in the 1980s. And the result is far from guaranteed. Unlike a bank robbery, where the stolen money can be hidden, Bitfinex bitcoins have never really been "lost". Tools have been developed over the past few years to allow law enforcement and regulators to automate cryptocurrency tracking across thousands of transactions, across blockchains.