Abstract
This chapter talks about criminals that have always utilized jurisdiction borders as a means of evading prosecution or disrupting investigation. It looks at how a covert investigation contained within a single local English police force may have transnational actions associated with it. It also mentions instruments and conventions that have been created to facilitate mutual legal assistance and international law enforcement cooperation. The chapter explores how domestic investigators can secure help as required in their own investigation where evidence or the suspect is located outside their own jurisdiction. It emphasizes how different domestic jurisdictions must work alongside each other in cooperation when criminality crosses their mutual border in the absence of an international or supranational criminal code.