Performing qualitative research through direct interviews enables researchers to obtain data and information that cannot be obtained in quantitative research. The access to individual conditions of certain attitudes or actions gives a huge opportunity of exploration of various research areas. Each researcher must meet strict ethical standards before committing to the study to prevent harming or exposing the participants. However, the law clearly imposes the need to disclose the knowledge about committed crimes. In this article we will present which specific crimes should be reported according to the Criminal Code. We will also consider whether, in this case, the researcher can provide the participants full anonymity and confidentiality. We also indicate if it is necessary to inform the participants that some content of an interview may be reported to law enforcement agencies and what implications it may have for the conducted research.