This chapter aims at discussing how social media intelligence (SOCMINT) can be and has been applied to the field of criminal justice. SOCMINT is composed of a set of computer forensic techniques used for intelligence gathering on social media platforms. Through this chapter, readers will be able to better understand what SOCMINT is and how it may be helpful for criminal investigation and national security. Different aspects of SOCMINT are addressed, including application in criminal justice, intelligence gathering, monitoring, metadata, cyber profiling, social network analysis, tools, and privacy concerns. Further, the challenges and future research directions are discussed as well. This chapter is not meant to serve as a technical tutorial as the focus is on the concepts rather than the techniques.