Previous studies had shown that IF exhibits a relatively large variation among Asians, but not among Causasians. The results of the current research revealed population data that fitted the Hardy-Weinberg law. In addition, phenotyping was possible using bloodstains that had been stored at 37 degrees Celsius for up to 1 week, at room temperature for up to 2 weeks, and at 4 degrees Celsius for up to 5 weeks. Findings indicated that the IF system can be a useful supplement for the forensic identification of bloodstains, although it seems useless for identifying Caucasians. Figures, tables, and 8 references (Author abstract modified)