Studies were performed to define the typing conditions and evaluate the forensic applicability of multiplex amplification of three STR loci, CSF1PO, TPOX, and THO1. Results were obtained using the GenePrint STR System (Promega Corporation, Madison, WI) Kit. To determine the utility of the GenePrint STR System for forensic casework analyses, the following experiments were conducted: 1) analysis of mixed body fluid; 2) determination of the sensitivity of detection; and 3) evaluation of results from biological samples from casework. In addition, the following simulated forensic conditions were assayed to detect whether or not there may be adverse effects on the ability to type these loci: 1) chemical contaminant effects on the DNA in body fluid samples; 2) the effects on DNA from samples deposited on various substrates; 3) the consequences of micro-organism contamination; and 4) the effect of sunlight and storage conditions on the integrity of the STR profiles/DNA. The data demonstrate that STR typing of biological samples exposed to a variety of environmental insults yields reliable results and that the analysis of the STR loci CSF1PO, TPOX, and THO1 can be applied in a forensic setting.