FORT LAUDERDALE, Fla. (AP) — Trial began Tuesday for a former top executive at Swiss banking giant UBS AG on charges of conspiring with other bankers and thousands of wealthy Americans to conceal $20 billion in assets from the IRS.

Raoul Weil, who once ran the global wealth management operations for UBS, faces up to five years in prison if convicted of conspiracy to defraud the U.S. government. Prosecutors say he oversaw a lucrative, illegal business in the U.S. that recruited the wealthy to hide money behind opaque Swiss bank secrecy laws and using phony companies, foundations and other entities.