Human trafficking, commercial sexual exploitation and modern slavery have experienced an unprecedented boom over the past decade due to the development of information and communication technologies (ICTs), particularly in digital and networked environments. These developments have created new opportunities for human exploitation and illegal profiteering. Adult Services Websites (ASWs), online platforms on which sex workers post profiles advertising their services, are a key conduit for human traffickers to exploit their victims. Alongside profiles of independent sex workers, traffickers are posting false ASW profiles, advertising the forced services of their victims and camouflaging these false profiles amongst legitimate adverts. In response, police practitioners are proactively investigating ASWs to identify suspect profiles. A key obstacle for practitioners, however, is to distinguish between ASW profiles posted by independent, consenting sex workers advertising their services, and those posted by traffickers exploiting their victims. The exploratory study presented in this paper seeks to address this particular challenge. Working with a British police force, the researchers in this study gathered existing knowledge on the traffickers' use of ASW profiles to create a bespoke tool of analysis, the Sexual Trafficking Identification Matrix (STIM). The aim of this tool has been to identify 'risk indicators' on ASW profiles and to flag these for potential police investigation. This paper presents the results of this exploratory study and its four stages. Furthermore, more broadly, it reflects on the use of evidence-based tools by law enforcement to tackle complex domains of offending such as those of human trafficking and commercial sexual exploitation.