Prosecutors are investigating about 100 professors across the country on suspicion they took bribes to help students get their doctoral degrees.
The investigation is focused on the Institute for Scientific Consulting, which allegedly acted as the intermediary between students and professors.
According to Focus magazine and the newspaper Neue Westfaelische, students paid $5,700 to $28,500 to the company, which promised to help them get doctoral degrees through its extensive contacts within university faculties.
Neue Westfaelische said hundreds of students were involved. It was not clear whether the students knew that bribes were being paid.