[Photo: Cayambe own work / Wikimedia Commons]

Shortly after Credit Suisse pleaded guilty in May 2014 to aiding tax evasion, Justice Department discovered similar activity at another unit

Less than 3 years after Credit Suisse paid billions and pleaded guilty to aiding tax evasion through its desk serving American clients, the Swiss bank is a focus of a sprawling new investigation into whether another unit kept doing the same thing.

The latest probe could lead to an indictment of Credit Suisse, fresh penalties or a potential curtailing of some business - and highlights the difficulties prosecutors face in fulfilling promises to crack down on corporate misconduct.

INVESTIGATING THE BANK’S ISRAELI DESK.    The U.S. Justice Department in July 2014 discovered that American professor Dan Horsky was potentially hiding money overseas in his CS accounts managed by the bank’s Israel desk. That was just 2 months after Credit Suisse’s May 2014 guilty plea to aiding tax evasion, and related $2.6 billion settlement.

Within a year, Mr. Horsky was cooperating in the department’s resulting investigation, surreptitiously recording his Credit Suisse bankers and helping build yet another case against the bank, according to court documents and people familiar with the matter. Mr. Horsky was recently sentenced to 7 months in prison and prosecutors are weighing whether to punish Credit Suisse a 2nd time.

The New York Department of Financial Services, which has the ability to revoke Credit Suisse’s charter in the U.S., also has opened an investigation.

Yet it wasn’t until late 2015 that the Justice Department reportedly informed Credit Suisse’s general counsel, Romeo Cerutti, that investigators had flagged an unspecified issue at the bank’s desk serving Israeli clients. They instructed him to do nothing about it to avoid interfering with their examination. That put Mr. Cerutti in the awkward position of having to stand by as a fresh probe into a painful issue from the bank’s past unfolded.

The senior manager and 4 other Credit Suisse employees from the Israel desk were later suspended by the bank, after it was fully briefed by the Justice Department on its probe last year.

It isn’t clear how Mr. Horsky’s accounts first drew attention. The SEC also is investigating the new allegations.