Drawing on a 3-year research project that examined police uses of the NDNAD, chapters describe the complex and changing relationships between scientific knowledge and police investigation that have shaped the forensic applications of DNA profiling. The uses of DNA profiling are illustrated by its use in major British criminal cases in which DNA evidence has been presented and challenged. The chapters describe a number of important scientific, technical, legislative, and policy developments that have transformed the forensic uses of DNA in England and Wales. Throughout the book the authors argue that at least four key changes have provided the foundation for the priority given DNA within British policing. First, there was the redefinition of what constituted an intimate sample, which allowed the mass use of a sample and cheap collection technique (the buccal scrape) by police officers. Second, the criteria for NDNAD inclusions have been gradually expanded, so that the database now contains any person arrested on suspicion of a recordable offense. Third, the law has changed to allow samples and profiles obtained from all suspects to be held indefinitely. Fourth, a national funding program supported by new forms of performance measurement has had a significant role in shaping police scientific support work and the subsequent population and uses of the NDNAD. 229 references