These authors describe the development of GIS-based data analysis software named Criminal Path finder, or C-PAT. The existing database of information was integrated with the map software, using the location address as a key field. Also, vector digital maps were used as data sources in investigations. This article provides the specifications of the software, such as data importing and mapping that make Microsoft Access files importable; data scanning is possible by overlaying aerial photographs and residential maps to grasp the detail of crime scenes, with a 3D-VIEW capability for emergency cases; spatial query makes it possible to retrieve records using their spatial relationship such as traffic surveillance cameras near crime scenes; and attribute query is possible because C-PAT also supports attribute, non-spatial queries from existing database, such as retrieving automobiles that have frequently passed the crime scene from the traffic surveillance system. It is reported, in summary, that C-PAT supports crime mapping, data management, and decision making by the supervisor during an investigation, thus saving on human resources. Also, the merits of a developing method of prototyping are discussed as a way to involve the end-user, the police officer, in the development of the software, thus reflecting the needs and wants of the end-user in its specifications.