ABSTRACT
In the past, the standard practice in forensic biology casework analysis typically included a preliminary screening of evidentiary items recovered during the investigation of criminal oenses in order to identify the presence, and possible tissue origin, of biological material. Typically, conventional methods for body uid stain analysis are carried out in a serial manner, with a portion of the stain being tested for only one body uid at a time. Frequently, multiple tests are required to rst presumptively identify the presence of biological uids, followed by additional testing in order to conrm the presence of the uid or identify the species of origin. erefore, these methods are costly not only in terms of the time and labor required for their completion, but also in the amount of sample consumed. Although these conventional methods can conrm the presence of human blood and semen, none of the routinely used serological and immunological tests can denitively identify the presence of human saliva, vaginal secretions, or menstrual blood. With the large volume of cases that operational crime laboratories are faced with processing every year, signicant time and resources are devoted solely to the screening of evidentiary items for the presence of biological materials. e inability to positively conrm the presence of certain biological uids, the consumption of portions of valuable, limited samples, and the time and labor required, have resulted in a trend to bypass conventional body uid identication methods and proceed straight to the analysis of any DNA present in forensic samples. e disuse or infrequent use of body uid identication methods could prevent the recovery of probative information crucial to the investigation and prosecution of the case. For example, consider a sexual assault on a female victim with an object (recovered from the suspect) where the victim’s DNA is recovered from the object. He could claim that the victim handled the item during previous casual encounters and this would be why her DNA was present. However, the signicance of this evidence would increase if the source of the DNA could be shown to originate from vaginal epithelial cells, a circumstance that would be consistent with a sexual encounter but not with casual handling. Currently there is no test available to positively identify the presence of vaginal secretions. erefore, the routine use of highly specic body uid identication methods prior to DNA analysis awaits the development of suitable molecular-genetics-based methods that are fully compatible with the current DNA analysis pipeline.
