Even before the weekend collapse of Signature Bank, U.S. prosecutors already had the firm in its sights.

Signature Bank was being examined for its work with crypto clients, according to Bloomberg.

Justice Department investigators in Washington and Manhattan were examining whether the New York bank took sufficient steps to detect potential money laundering, such as monitoring transactions for signs of criminality.

The Securities and Exchange Commission was also looking into it, according to people familiar with the situation.

SIGNATURE BANK SHUT DOWN IN CONNECTION WITH SILICON VALLEY BANK COLLAPSE

FOX Business has reached out to Signature Bank and FDIC for comment.

The FDIC took control of the bank.

 SEC Chair Gary Gensler released a statement over the weekend when authorities took steps to bolster US lenders and shut Signature.

"We will investigate and bring enforcement actions if we find violations of the federal securities laws," the SEC chief said at the time.

REGIONAL BANKS 'REASONABLY STABLE' BUT REGULATORS NEED TO PROVIDE 'MORE CLARITY': FORMER FDIC CHAIR

The bank and its staff haven’t been accused of wrongdoing, and the investigation could end without further action.

The FDIC is looking for a buyer for Signature.

Regulators have been pressuring banks and other regulated firms to pull back from digital currencies and other assets to head off potential risks to the financial system.

Signature failed following the demise of Silvergate Capital which also catered to the crypto industry, and Silicon Valley Bank.

SVB COLLAPSE: MOODY'S FLAGS SIX OTHER BANKS WITH CONCERNING CREDIT RATINGS

After 40 years, Silicon Valley Bank, the nation’s 17th largest, was shut down by the FDIC Friday as regulators moved to protect customers as it faced a liquidity crunch after losing $2 billion. 

CLICK HERE TO GET THE FOX BUSINESS APP

It became the largest bank failure since the financial crisis. 

All three banks now face US scrutiny.