The mobility of career criminals and their tendency to repeat successful methods of operation in different police jurisdictions makes it imperative that police agencies cooperate with one another in identifying large scale theft operations, conducting surveillance of suspects who travel between jurisdictions, and obtaining and using evidence derived from crimes committed by the same criminals in various jurisdictions. The value of such cooperation between police agencies was shown in uncovering and terminating the operations of a jewelry theft ring operating not only throughout the Chicago area, but in other States as well. Central to the success of the police operation was the work of the central investigation unit of the Chicago Police Department, a unit specifically established to promote interagency cooperation. The unit maintains updated information on many career criminals, their criminal specialties, and their methods of operation. Circulars on career criminals believed to be operating in the area are regularly provided other departments. With the help of this unit, police agencies from various jurisdictions that had experienced jewelry thefts from the ring conducted surveillance and evidence collection that built a successful case against the members of the ring and their fence, who had ties to organized crime. Seven steps are listed which can help jewelry stores reduce their losses from theft, and procedures police departments can take to prevent such theft are outlined as well.