The paper presents the considerations about the police use of information obtained from open sources. Thoughts are based on studies on police intelligence and investigation, also on the literature in this field as well on the authors professional experience. The article describes the method of open-source intelligence and points to the possibility of using overtly-source information in the prevention, detection and combating of crime. The reference to the principles of legality and opportunism is intended to explain legal and practical aspects of the handling of the information obtained from open sources.