These are crooks who set up elaborate schemes ("sting operations") to extract money from unsuspecting people and financial institutions. They establish "front" or "phantom" firms and offices throughout the world. They tempt the gullible by offering them enormous, immediate, tax-free, effort-free, profits. They let the victims profit in the first round or two of the scam. Then, they sting: the victims invest money and it evaporates together with the dishonest operators. The "offices" are deserted, the fake identities, the forged bank references, the falsified guarantees are all exposed (often with the help of an inside informant).
Probably the most famous and enduring scam is the "Nigerian-type Connection". Letters - allegedly composed by very influential and highly placed officials - are sent out to unsuspecting businessmen. The latter are asked to make their bank accounts available to the former, who profess to need the third party bank accounts through which to funnel the sweet fruits of corruption. The account owners are promised huge financial rewards if they collaborate and if they bear some minor-by-comparison upfront costs. The con-men pocket these "expenses" and vanish. Sometimes, they even empty the accounts of their entire balance as they evaporate.