Understanding criminal investigation – as would be the case for any part of criminal justice – cannot properly be realized without having some sense of its historical and social context. It is providing this context that is the focus of the chapters in this first part of the volume. The part opens with Bob Morris’s overview of the history of criminal investigation. In outlining the changing nature and organization of criminal investigation he identifies four main periods: what he refers to as the ‘heroic period’ covering the first 50 years after the introduction of the New Police; a further period lasting until the interwar years in which a process of organizational specialization got underway; and a third half-century-long period in which there developed central leadership and oversight of criminal investigation within the police service. Finally, there is the current era, starting in the early 1980s, in which further centralization, particularly by government, took hold and moulded crime investigation practices. What is clear from Morris’s analysis of the history of investigation is that the forces that have shaped and changed policing generally are also those that have affected investigation more particularly. Though there are particular incidents – scandals, inquiries and serious crimes – that obviously bear on investigation much more significantly than other aspects of police work, in general terms it has been the gradual centralization, politicization and increasing managerial control of policing that can also be seen in investigation as elsewhere.