The purpose of the article is a scientific analysis of the activity of detection, disclosure and investigation of criminal offenses. Such activity is a specific type of professional socially useful activity carried out by subjects (investigator, inquirer, operational unit employee, detective, etc.) with the aim of establishing the truth, based on procedural evidence in criminal proceedings. It has been proven that the construction of a coherent, logically consistent, comprehensive system of scientific knowledge, which characterizes the activity of detection, disclosure and investigation of criminal offenses, is still ongoing in criminology. It is concluded that the successful detection of criminal offenses can be carried out only when the subject of activity adheres to the principles of ensuring the necessary effectiveness. For the successful implementation of such principles, not only forensic knowledge is needed, but also the creation of a certain integrated system of detection of criminal offenses. The structure of detection of criminal offenses is proposed, which can become the theoretical basis of such a system. The author came to the conclusion that in criminology, a criminal offense is considered to be solved on the condition that the factual circumstances essential for the resolution of the proceedings, as well as the person who committed this offense, are established. The detection of a crime is not something separate from the investigation or something that complements it, but should be considered as its informational, cognitive, technological aspect, which distinguishes a complex of forensic operations, methods, techniques and means for a consistent, step-by- step solution to the strategic and tactical tasks of the pre-trial investigation of criminal offenses It is shown that the structure of activities for the investigation of criminal offenses includes the following main elements: the subject of activity (makes all decisions on carrying out certain procedural actions); functions of the subject of activity (search and cognitive functions are recognized as the main ones); the purpose of the activity (establishing the truth in criminal proceedings and creating appropriate conditions for the correct application of the law); procedural tasks, which are solved in the form of tactics (detection of the crime, exposure of the guilty, provision of compensation for the damage caused by the offense, etc.); general object of activity (cognition by the subject of activity of an event with signs of a criminal offense); subject of activity (forensically significant information). The mechanism of direct implementation of the activity of detecting disclosure and investigation of criminal offenses is analyzed. Its exploratory and cognitive, problem-solving, situational and sometimes urgent character was established. It has been proven that from the point of view of criminology, establishing the truth during the detection, disclosure and investigation of a criminal offense means mentally recreating (according to the collected factual data) the investigated event in its essential legally significant features, with the subsequent reflection of its mental model-image in the relevant procedural documents . It was concluded that effective, i.e., fast, rational, high-quality and productive activities for the detection, disclosure and investigation of criminal offenses are impossible without proper organizational support, which means the creation of the necessary conditions (prerequisites) for the subject to optimally achieve the goal of this activity.