Wegelin pleaded guilty in Manhattan federal court in January to conspiring to help hide more than $1.2 billion in assets from the IRS, while opening undeclared accounts for at least 70 U.S. taxpayers who were former UBS clients. The bank, which paid $74 million to resolve the investigation, closed its doors after 272 years.

Some of Singenberger’s actions are described in the U.S. indictment of Hans Thomann, a UBS client adviser from 1993 to 2003, who later worked for Swiss asset-management firms. Thomann travelled often to New York to deliver cash to or accept cash from one client, according to his indictment.

The Introduction

At one meeting, Thomann recommended that a client meet Singenberger.

“A few moments later, Singenberger appeared at the room in which Thomann was staying at the Manhattan hotel,” according to the indictment. Thomann said he and his UBS colleagues “recommended to U.S. taxpayers who had undeclared accounts at UBS that they use the services of Singenberger.”

The client later flew to Zurich, where Singenberger set up a second UBS account under the name of a British Virgin Islands corporation, according to the indictment.

Thomann was charged with conspiracy in March 2012 in federal court in New York. He hasn’t answered the charge in court. He couldn’t be reached for comment.

Both Thomann and Singenberger helped Canale, the retired Army surgeon, according to Canale’s charging document, known as a criminal information.

Inherited Account

Thomann had handled the account of a relative who died in 2000, leaving the money to Canale. Thomann introduced Canale to Singenberger to set up a structure that “would, to the greatest extent possible, obscure from the IRS” his ownership of his undeclared account, according to the information.