Since the Siemens corruption case and the subsequent handling of the violations by the company, compliance and internal investigations have become indispensable in Germany. In the course of internal investigations, companies regularly cooperate extensively with law enforcement authorities to clarify suspicions or identified misconduct as promptly and quietly as possible. This leads to a multitude of legal and factual issues. The work presents the conflicts arising from this, taking into account the corruption cases of Siemens and MAN, and proposes solutions. The focus is on the analysis of employee surveys and amnesty offers by the company, with a follow-up question regarding the admissibility of the insights gained in criminal proceedings.