This chapter introduces the field of investigative linguistics, which is defined as the systematic application of techniques for linguistic analysis to uncover information about current events that are of concern to the general public, especially but not limited to cases of disputed authorship. A distinction is made between those forensic linguists who act as investigators, primarily working for law enforcement helping to identify suspects, and those who act as expert witnesses, primarily working for the courts providing linguistic evidence to support the prosecution or defence. In addition, this chapter innovatively extends the term investigative linguistics to include linguistic investigations into newsworthy events, i.e. linguists acting as or with investigative journalists. Two cases of disputed authorship are presented to illustrate these two forms of investigative linguistics: the investigation into the disappearance of Debbie Starbuck, which was conducted on behalf of law enforcement, and the investigation into the authorship of the paper that introduced Bitcoin, which was conducted independently and then released to the press. This chapter concludes by considering the similarities between these two forms of investigative linguistic analysis.