A trio of Swiss bankers has been charged with conspiring to help with U.S. taxpayers hide more than $1.2 billion in assets from the Internal Revenue Service.

The three bankers, Michael Berlinka, Urs Frei and Roger Keller, worked as client advisers at the Zurich branch of the Swiss bank Wegelin & Co., which provides private banking, asset management, and other services to clients around the world, according to an indictment handed down against them Tuesday. Wegelin is the oldest private Swiss bank.

Berlinka, Frei and Keller allegedly opened and serviced dozens of undeclared accounts for U.S. taxpayers in 2008 and 2009, in an effort to capture business lost by UBS AG after news spread that the IRS was investigating UBS for helping U.S. taxpayers evade taxes and hide assets in Swiss bank accounts. After the reports, UBS stopped servicing undeclared accounts for U.S. taxpayers.

To capitalize on the business lost at UBS, the three bankers at Wegelin allegedly told various U.S. taxpayer-clients that their undeclared accounts at the bank would not be disclosed to U.S. authorities because Wegelin had a long tradition of bank secrecy. The defendants and other client advisers at Wegelin also told their U.S. taxpayer-clients that the bank was less vulnerable to U.S. law enforcement pressure because, unlike UBS, the bank did not have offices outside Switzerland. Members of Wegelin’s senior management participated in some of these sales pitches to U.S. taxpayer-clients who were fleeing UBS.

To further the conspiracy, Berlinka, Frei, Keller, and/or other client advisers allegedly opened and serviced undeclared accounts for U.S. taxpayer-clients in the names of sham corporations and foundations formed under the laws of Liechtenstein, Panama, Hong Kong and other jurisdictions for the purpose of concealing the identities of their U.S. taxpayer-clients from the IRS.

They also allegedly received and retained documents that falsely declared that the sham entities were the beneficial owners of certain accounts when, in fact, the accounts were owned by U.S. taxpayers. Prosecutors said they also permitted some of their U.S. taxpayer-clients to open and maintain undeclared accounts at Wegelin using code names and numbers to minimize references to the actual names of the U.S. taxpayers on Swiss bank documents.

The three also allegedly ensured that account statements and other mail for U.S. taxpayer-clients were not mailed to them in the United States. They sometimes communicated with U.S. taxpayer-clients using their personal email accounts to reduce the risk of detection by law enforcement.

Berlinka, Frei and Keller all reside in Switzerland. If extradited to the U.S., each faces up to five years in prison, three years of supervised release, and a fine of the greatest of $250,000, or twice the gross pecuniary gain derived from the offense or twice the gross pecuniary loss to the victims.

The three continue to be employed by Wegelin, according to Bloomberg Businessweek, but the bank no longer services U.S. clients and is currently negotiating with U.S. officials.