The flash mob phenomenon has been well studied in sociology and other disciplines, but not in the area of digital forensics. Flash mobs sometimes become violent, perpetrate criminal acts and pose threats to public safely. For these reasons, understanding flash mob activities and identifying flash mob organizers are important tasks for law enforcement. This chapter presents a technique for extracting key online behavioral attributes from a popular Hong Kong discussion forum to identify topic authors – potential flash mob organizers – who belong to a vocal minority, but have the motivation and the ability to exert significant social influence in the discussion forum. The results suggest that, when attempting to interpret flash mob phenomena, it is important to consider the online behavioral attributes of different types of forum users, instead of merely using aggregated or mean behavioral data.