The research explored two alternative hypotheses. One predicted that rapists would commute into an area to carry out their offense. The second predicted that they would make forays from a fixed location. The analysis revealed that 39 of the offenders fitted the marauder hypothesis. However, the area covered by this model was an average of nearly 180 square miles. A second complementary theory, developed from aspects of offenders' backgrounds, was therefore used to refine the predictions of distance traveled to and between offenses. This theory enabled the size of the residential zone predicted from the marauder model to be reduced to an average area of just over 10 square miles. Tests of these models, combined into a small-scale expert system, predicted the correct area for 82 percent of the cases. Further development of this expert system is recommended. Figures, table, and 11 references (Author abstract modified)