Denmark’s largest bank said it was under criminal investigation by U.S. law enforcement over a massive scandal involving its Estonian branch, which may have helped launder millions of dollars from Russia and elsewhere.

Danske Bank's announcement October 4 was the latest sign of deepening trouble at the Danish lender.

The U.S. Justice Department joins other previously disclosed probes by the European Banking Authority and Britain's National Crime Agency, as well as Denmark's own regulators.

"Danske Bank has also now received requests for information from the US Department of Justice (DOJ) in connection with a criminal investigation relating to the bank's Estonian branch conducted by the DOJ," the bank said in a statement posted on its web site.

The bank has said its own probe has turned up more than $200 million in suspicious transfers made through its Estonian branch. Much of the money came from Russia and other former Soviet republics.

The scandal has already forced the resignation of the bank's CEO.

Danish regulators said in August that the funds may be linked to a tax fraud case that was originally uncovered in 2007 by a Russian whistle-blower named Sergei Magnitsky.

Magnitsky was later imprisoned, and charged with the crimes he helped discover. He died in a Moscow jail in 2009 after being denied medical care.

His death resulted in a 2012 U.S. law that was named for him, a law that infuriated the Kremlin and continues to reverberate through U.S.-Russian relations.

With reporting by Reuters