Mining Criminal Networks from Chat Log

Cyber criminals exploit opportunities for anonymity and masquerade in web-based communication to conduct illegal activities such as phishing, spamming, cyber predation, cyber threatening, blackmail, and drug trafficking. One way to fight cyber crime is to collect digital evidence from online documents and to prosecute cyber criminals in the court of law. In this paper, we propose a unified framework using data mining and natural language processing techniques to analyze online messages for the purpose of crime investigation. Our framework takes the chat log from a confiscated computer as input, extracts the social networks from the log, summarizes chat conversations into topics, identifies the information relevant to crime investigation, and visualizes the knowledge for an investigator. To ensure that the implemented framework meets the needs of law enforcement officers in real-life investigation, we closely collaborate with the cyber crime unit of a law enforcement agency in Canada. Both the feedback from the law enforcement officers and experimental results suggest that the proposed chat log mining framework is effective for crime investigation.