Cologne prosecutors said Wednesday that dozens of investigators began searching the offices Tuesday of a Frankfurt-based financial institution and several auditing and tax firms.

The raids, which also targeted private apartments of four suspects, were linked to an investigation into so-called cum-ex share transactions and related tax evasion practices that are said to have cost the German government billions of euros, prosecutors said.

In a statement, JPMorgan confirmed that its Frankfurt offices were “visited” this week.

“We continue to cooperate with the German authorities on their ongoing investigation,” the bank said.

The offices of several rival institutions have already been searched by German authorities. Hundreds of bankers allegedly were involved in the cum-ex scheme that saw participants claim reimbursement for taxes they hadn’t paid.

German Chancellor Olaf Scholz has come under scrutiny for the way Hamburg authorities handled a related case while he was mayor of the city.