This is the Final Report of a project that assessed the effectiveness of using a processing protocol for sexual assault samples that involved rapid DNA instrumentation.
Due to the nature of rape and sexual assault, the evidence collected in investigating these crimes is often a mixture of DNA from two or more individuals, with the victim’s DNA being most prominent in the evidence sample. The differential extraction process was developed to increase the likelihood of obtaining a DNA profile from the assailant. This is a lengthy procedure when done manually and requires additional robotic equipment for automation. A new method was developed by ANDE that supports the rapid processing of sexual assault samples. It involves a short pre-processing step that uses basic laboratory equipment in separating the alleged victim’s DNA from the perpetrator’s DNA and enables the production of the DNA profiles on the I-Chip. The I-Chip is designed to process samples with low DNA content. Although this data is not currently eligible for upload to or searching against the national DNA index system (NDIS), it can be used to search against locally controlled databases. This could enable faster identification of the perpetrator. Using the evaluation methodology described in this report, it was determined that the ANDE method provided actionable DNA profiles for most samples tested and produced more single-source profiles than traditional typing. In a comparative analysis, traditional typing methods were generally more sensitive than the rapid method, thus providing more data overall; however, it resulted in more mixed profiles than the rapid method. 7 tables, 6 figures, and 8 references
810 Seventh Street NW, Washington, DC 20531, United States