The U.S. Attorney for the Southern District of New York earlier this week charged three current and former client advisors at Swiss bank Zuercher Kantonalbank with conspiring with at least 180 U.S. taxpayers and others to hide more than $420 million in offshore accounts from the Internal Revenue Service.

The three bankers -- Stephan Fellman, Otto Huppi and Christof Reist -- are alleged to have conspired to hide Swiss bank accounts and the income generated by them from the IRS, by opening and managing undeclared accounts using code names such as “Raincity” and “Kakeycat,” or in the names of sham corporate entities, to conceal the actual holders of the accounts.

They are also alleged to have helped clients access their hidden funds by various means, and Huppi, a U.S. citizen, is alleged to have advised a client not to disclose an undeclared client. Huppi is no longer with ZKB, which said that it has exited business with American clients.

All three reside in Switzerland, and have not been arrested. If convicted, they face up to five years in prison, and as much as $250,000 in fines.