CTF (Capture The Flag), which aims to search for clues about missing persons, is a structured open source intelligence (OSINT) activity where investigators and volunteers collaborate to find relevant clues about missing persons. This type of exercise has a humanitarian objective and is carried out in a controlled, ethical and safe manner. Inspired by initiatives such as Trace Labs (Canada) or Project Horus (Spain), the format consists of teams that receive real cases (with authorization and monitoring by the authorities) and have the mission of finding useful information through open sources: social networks, forums, public databases, images, metadata, among others. The results are presented in the form of structured and verified evidence. Each lead is evaluated by judges with experience in OSINT, ensuring its relevance, validity and traceability.