On 14 and 15 March, the NGO LingvaLexa delivered a training on the use of open sources of information in war crimes investigations for prosecutors of Sumy. During the training program, special attention was paid to the issues of information hygiene and security in the context of full-scale russian invasion. Participants gained not only technical skills in data collection and analysis, but also important tips on how to protect personal information. Various aspects of using open sources were discussed, as well as methods of protection against possible threats. The trainers also drew attention to other important aspects of OSINT, such as social media analysis and disinformation recognition. Participants had the opportunity to interact and share experiences with colleagues. The final part of the training was devoted to discussions and solving practical tasks, which allowed the attendees to consolidate their knowledge. The training aimed not only at teaching prosecutors how to use OSINT tools, but also to provide them with understanding of the importance of security and information protection in the face of modern challenges and threats.