The U.S. Government’s investigation of cross-border business by UBS and alleged tax evasion by some of the firm’s US clients has resulted in an indictment of Raoul Weil, Chairman and CEO of UBS Global Wealth Management and Business Banking.

A grand jury in South Florida delivered the indictment of Weil, who was head of Global Wealth Management International from 2002 through 2007 when the alleged activity occurred. Marten Hoekstra, head of Wealth Management Americas, will replace Weil on an interim basis.

Weil faces up to five years in prison and $250,000 in fines. But the firm and other executives could pay a bigger price. The indictment also included unnamed UBS executives in “the highest level” positions and some U.S. clients of the bank as co-conspirators in the case.

The firm’s U.S. tax evasion trouble was revealed in May when banker, Bradley Birkenfeld, was charged with helping billionaire Orange County, California, real estate developer Igor M. Olenicoff evade U.S. taxes on $200 million hidden in Swiss and Liechtenstein bank accounts. Birkenfeld pleaded guilty in June and is cooperating with federal prosecutors. He is expected to be sentenced in June.

This latest indictment indicates the Justice Department suspects the Swiss firm illegally helped up to 20,000 American clients hide $20 billion in secret offshore accounts, thus evading $300 million a year in taxes from 2000 to 2007. Not only that, the bank is alleged to have trained bankers and other personnel to avoid detection by U.S. authorities with cloak-and-dagger techniques such as changing hotels and using encrypted laptop computers.

“Professionals, including bankers, who promote fraudulent offshore tax schemes against the United States, will be held accountable," John Marrella, deputy assistant attorney general of the Justice Department's tax division, said in a statement. “These individuals face severe consequences including imprisonment and substantial fines,” he said.

UBS stopped offering offshore Swiss bank accounts to U.S. citizens shortly after Birkenfeld was charged. The bank was recently described by U.S. President-elect Barack Obama as one of the banks that helped “tax cheats.”