While an effective criminal investigative process involves a coordinated effort among many units in the police agency, primary responsibility rests with the patrol and investigative units. Improvements in the criminal investigation process can only be effective if a police agency adopts a creative patrol strategy followed by a responsive criminal investigation process that directs resources into those areas with the greatest potential for success. A Rand investigation of the criminal investigation process has found that patrol practices and citizen response and cooperation are more important determinants of criminal apprehension than refinements in the investigative process. This suggests a substantial shift of police resources from investigative units to other units. Since police resources are limited, the effectiveness of police investigations will be increased if resources are allocated only to those crimes that have a chance of solution, which involves identifying solvability factors (information about a crime which can provide the basis for determining who committed that crime). Criminal investigations can be classified into three broad areas: (1) preliminary investigations (initial action by the police agency in reponse to a report that a crime has occurred), (2) followup investigations (continues much of the work begun during the preliminary investigation), and (3) special subject investigations (efforts focusing on particularly sensitive areas of criminal activity). Criminal investigation involves more than the deductive processes of verification, identification, and other tasks connected with solving a crime. It also entails helping the prosecuting attorney develop the best possible case for presentation to a grand jury and for trial, providing information to the victims and soliciting their help, dealing with the special problems of juvenile cases, and working out improved investigative methods for dealing with career criminals. Managing the investigative process involves coordination and communication, supervision of the investigative process, the selection and training of investigators, and assessment of investigative results.