The scientific search for the peculiarities of evidence in the course of investigation of criminal offences under Parts 1 and 2 of Article 111-1 of the Criminal Code of Ukraine is due to the fact that with the beginning of the full-scale invasion of Ukraine by the Russian Federation, collaborationism at the level of national legislation, scientific doctrine and higher legal education has acquired a fundamentally new meaning. It is also advisable to take into account the fact that the historical basis of collaboration is treason, the normative consolidation of which has its roots in Roman law. Information and psychological operations, dissemination of relevant narratives to the formation of attitudes and orientations among the population, which may later become the basis for committing criminal offences under Parts 1, 2 of Article 111-1 of the Criminal Code of Ukraine. At the level of changes in the criminal procedure legislation, current trends and approaches to pre-trial investigation, the basic principles and features of pre-trial investigation of collaboration activities have been rethought. It is substantiated that in modern conditions, evidence in the course of investigation of criminal offences under Parts 1, 2 of Art. 111-1 of the Criminal Code of Ukraine is inseparable from taking into account the features of modern equipment which can be used for information transmission, analysis of computer information and information from correspondence, channels and groups in social networks containing valuable information, samples of signatures, seals and other details of documents which reflect information about the collaboration activities of individuals and groups. Other relevant features of evidence in the course of investigation of criminal offences under parts 1, 2 of Art. 111-1 of the Criminal Code of Ukraine include: the need to conduct as many investigative (search) and procedural actions as possible, including specific forensic examinations, of which one of the most common is the technical examination of document details; interaction of pre-trial investigation bodies and the public in the course of exchange of orientation information of investigative and inquiry units with volunteers, local activists, representatives of NGOs, writers, representatives of the scientific and creative intelligentsia, i.e. conscious and patriotic citizens who refused to cooperate with the occupation administration during the occupation and actively resisted it. Such interaction in the specific security conditions of martial law does not necessarily require face-to-face communication. Public messages on Twitter, Instagram, Facebook, and TikTok, which may contain information about persons involved in collaboration activities, their relationships with local residents and/or the occupation administration, etc., have significant potential for providing orientation information.