Drawings and diagrams using traditional methods have a major disadvantage: extensive changes require considerable effort and time, and errors and erasures are obvious in the finished product. In contrast, computer-aided drafting (CAD) has made flawless drawings possible. CAD models can also indicate the flight paths of multiple projectiles that have struck walls, floors, ceilings, vehicles, and victims, thereby helping refine complex theories regarding the unfolding of a criminal event. The expansion of the personal computer market and the availability of user-friendly software make it possible for every police agency to use this technology. Creating a crime scene model begins with the decision about which point will be the absolute zero reference point. All subsequent points are measured and referenced to the zero point. Investigators can use a palmtop computer to gather data at the crime scene. They can later transfer the data to a larger system to complete the model with the addition of doors, windows, furniture, and evidence. The finished model can be viewed from any perspective in wireframe or solid mode. It can also be animated and transferred to videotape. CAD courses are available at high schools, community colleges, and law enforcement training facilities. Illustration