JPMorgan Chase’s offices in Frankfurt, Germany, are being raided by prosecutors based in Cologne in relation to the cum-ex tax evasion scandal that is estimated to have cost European governments more than $10 billion, mostly during the first decade of this century.

“We can confirm that our Frankfurt offices were visited this week,” a JPMorgan spokesperson said in a statement Wednesday to Bloomberg, The Wall Street Journal and the Financial Times. “We continue to cooperate with the German authorities on their ongoing investigation.”

Searches involving more than 50 officers began Tuesday at an unidentified bank and include the homes of four suspects and an auditing firm that isn’t a target in the probe, said a spokesperson for the Cologne prosecutors, who are investigating roughly 1,500 people in 110 cases tied to the scandal. Four cum-ex trials are underway in Germany against bankers and a lawyer. Four bankers were convicted in earlier cases.

JPMorgan is hardly the first bank to have its Frankfurt offices searched for evidence in the scandal, including email trails and written correspondence. Prosecutors raided Bank of America and Barclays locations in the city in March, and Morgan Stanley offices in May.

Cum-ex, the Latin terms for “with/without,” refers to a trading strategy that let investors buy, borrow and sell shares during a brief window surrounding a dividend payout. The timing of the flurry of transactions exploited a loophole in German tax code that allowed multiple parties to claim refunds on a tax that was paid just once. Tax authorities refunded at least €3.9 billion in faulty refunds between 2001 and 2011, Germany’s finance ministry has said, according to the Financial Times. German officials closed that loophole in 2012.