Open-source technologies (OSINT) are becoming increasingly popular with investigative and government agencies, intelligence services, media companies, and corporations [22]. These OSINT technologies use sophisticated techniques and special tools to analyze the continually growing sources of information efficiently [17]. There is a great need for professional training and further education in this field worldwide. After having already presented the overall structure of a professional training concept in this field in a previous paper [25], this series of articles offers individual further training modules for the worldwide standard state-of-the-art OSINT tools. The modules presented here are suitable for a professional training program and an OSINT course in a bachelor’s or master’s computer science or cybersecurity study at a university. In part 1 of a series of 4 articles, the OSINT tool RiskIQ Passiv-Total [26] is introduced, and its application possibilities are explained using concrete examples. In part 2 the OSINT tool Censys is explained [27]. This part 3 deals with Maltego [28] and Part 4 compares the 3 different tools of Part 1-3 [29].