BERLIN (AP) — Police raided sites in Germany on Wednesday as part of an investigation into a crime ring suspected of forcing Vietnamese people into prostitution after they were smuggled into the country.

Berlin prosecutors and federal police said the suspects allegedly put the victims to work in nail studios, massage parlors and “brothel-like operations.”

Police said around 169 officers searched eight properties in Berlin, Hamburg and the Baltic Sea resort of Timmendorfer Strand. They said the raids results from an investigation launched in June.

The main suspect, a 43-year-old Vietnamese woman, was arrested at her home in Berlin. Police and prosecutors said she was known to authorities from previous trafficking cases.

A 25-year-old Vietnamese citizen and a 64-year-old German man are under investigation for the suspected trafficking of foreigners and forced prostitution.

The trio are accused of profiting from the illegal presence in Germany of eight women and two men who allegedly paid off debts to smugglers by working for the main suspect.

The suspects are also accused of engineering acknowledgements of paternity and sham marriages to secure legal residency in Germany for the immigrants.