The Y-STR was found to be useful in establishing the minimum number of male contributors in stains from multiple DNA sources, as well as to confirm the multiple suspects who contributed to complex DNA profiles. The system was also able to detect and characterize a limited number of male cells in a stain that was too weak to yield any autosomal result. The most important use of the system may be in excluding individuals from complex DNA mixtures. Both the Y-linked loci DYS390 and DYS439 are suitable markers to add to existing STRs in forensic casework. Another Y-STR that is more polymorphic than DYS438 could be included in order to enhance the discrimination power of this Y-system. In the first sexual assault case, 10 stains were recovered from the crime scene and were submitted for DNA analysis Reference bloods were collected from the six suspects in the case. No vaginal swab from the victim was submitted for analysis. In the second case, two stains were recovered from inside the suspect's car. A third stain was taken from a clothing item found inside the car. The three stains were submitted for DNA analysis. The description of the DNA analysis addresses autosomal STR analysis and Y-STR analysis. 19 references