David Voreacos

Former Credit Suisse Group AG bankers who blew the whistle on their employer for helping wealthy Americans dodge taxes are now urging U.S. authorities to punish the bank beyond the $2.6 billion it paid as part of a guilty plea seven years ago.

Robert T. Brockman, a Houston software tycoon, was charged with using a web of Caribbean entities to hide $2 billion in income in what prosecutors called the largest U.S. tax case ever against an individual.

Smith will acknowledge wrongdoing to end a four-year U.S. tax investigation involving assets held in offshore tax havens.

Robert T. Brockman was just putting the finishing touches on a new private equity fund when worrisome news arrived. Law enforcement agents had raided the home of a tax lawyer in Texas who had worked for him.

The matter hinges largely on whether Smith was actually the beneficial owner of Caribbean entities that received proceeds from his company’s first private equity fund, according to people familiar with the case.

Businessman Lev Dermen, 53, was found guilty Monday as part of a scheme to cheat the IRS out of $512 million through a program designed to promote clean fuels.

The bank admitted that it helped hundreds of American clients hide more than $1 billion in assets from the Internal Revenue Service and agreed to pay $192.4 million to resolve a decade-long U.S. tax investigation.