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Case Study I:

During the investigation of a complaint of sexual assault with violence, a used condom was seized from the suspect’s residence. The complainant’s statement indicated that a condom had been used during the assault with violence but no ejaculation had occurred. Microscopic examination of washings from the condom showed the presence of some epithelial cells along with numerous bacterial cells. No spermatozoa were observed. Subsequent RFLP DNA typing results showed a mixed sample with significant lane mobility shifts in the evidentiary sample as compared to the known samples of both victim and suspect. PCR STR analysis was performed following amplification of the samples, with successful partition of the victim’s and suspect’s profiles.

Case Study II:

During an attempted murder investigation, a wool ski mask reportedly worn by the suspect was recovered. Conventional microscopic hair examinations were unsuccessful in attempting to associate the ski mask to the suspect. Stains suspected to be from saliva were isolated from the mask and were found to contain human DNA. Subsequent RFLP DNA typing analysis resulted in a single lane mobility shift for the questioned DNA. Polymerase Chain Reaction analysis was then attempted on the evidentiary sample as well as the suspect’s known sample. The results obtained successfully linked the ski mask to the suspect.