Lauren Schagel; Julie Valentine; Leslie Miles (Brigham Young University)
Faculty Advisor: Valentine, Julie (Brigham Young University, Nursing); Miles, Leslie (Brigham Young University, Nursing)
Question: What is the impact of time between assault and evidence collection on the development of CODIS eligible DNA profiles?
Learning Overview/Synopsis: After attending this presentation, attendees will understand the length of time between sexual assault and evidence collection can be extended to five to six days post-assault and develop an eligible STR DNA profile.
Impact on the Forensic Science Community: This presentation will impact the forensic community by providing individuals with knowledge about the length of time in which victims can receive a sexual assault forensic examination (SAFE) to obtain a DNA profile of their perpetrator.
Synopsis/Abstract: The methodology of the study is an exploratory, retrospective design of over 2,700 submitted and analyzed sexual assault kits from a Mountain West state in the United States. Review of the current literature on time between assault and evidence collection indicate male DNA (Y-STR DNA) can be recovered up to 7 days post-coitus from a cervico-vaginal swab and develop a Y-STR profile.
Findings: In our large-scale, retrospective study of 2,727 sexual assault kits, probative STR DNA CODIS eligible profiles were developed in 39% of kits. Generalized estimating equation (GEE) logistic regression analysis found that for every 24 hours that passes between assault and SAFE, there is a 10% reduction in the development of a CODIS eligible DNA profile. The longest length of time between assault and exam and development of CODIS eligible profile in our study was 122.5 hours, over 5 days. This finding supports the testing of DNA samples collected five to six days post sexual assault due to the possibility of developing a CODIS eligible profile.
Conclusion: This retrospective study is impactful due to large-scale of the sample size. The 2,727 sexual assault kits used in this study are representative of what sexual assault looks like in modern society.