The GAO analysis of 71 cases shows that cases were opened as terrorism investigations for several reasons: the subjects were believed involved in terrorist acts, the subjects were believed leaders or members of terrorist organizations, or the subjects were believed associated with or linked to terrorist groups. By projecting the responses to the questionnaires, the GAO estimates that almost 99 percent of the 17,500 investigations conducted by FBI were not extensive, that the subjects in 38 percent of the cases were US persons, and that information on individuals involved in 47 percent of the cases was recorded into FBI data bases. Finally, the analysis indicates that most cases are closed when no information is developed linking the subject to terrorist activities.