The purpose of this study is to investigate the probative value of collecting and testing samples outside traditional cavity swabs from the victim’s oral, vaginal (penile), and rectal areas in sexual assault collection kits. Swabs collected from various areas of the victim’s body, such as inner thighs and breasts, can yield quality DNA profiles that are often better than the profiles from cavity swabs. In this study, we refer to these swabs from various areas of the victim’s body as “dried stain swabs” and the swabs from the victim’s cavities as “OVRs”. Sexual assault evidence can be daunting, time consuming, and a bottleneck regarding DNA analysis. Some laboratories have implemented protocols to streamline processing of sexual assault evidence that calls for the testing of OVRs over dried stains to prevent backlog. However, this method leaves potentially probative samples untested. Our laboratory currently prioritizes “intimate samples” when selecting items from a sexual assault kit to carry forward for DNA analysis. These intimate samples could be OVRs, dried stains from covered areas of the victim’s body, and even the victim’s underpants. A review of sexual assault cases was done to determine the importance of evidence submitted outside traditional cavity swabs. All samples were processed using Promega technology, including extraction with DNA IQTM on Maxwell®16 or Maxwell®48, quantification with PowerQuant®, and amplification with PowerPlex® Fusion. Profiles developed from OVRs, dried stains and victim’s underpants were evaluated to determine if DNA foreign to the victim was present and if there was enough foreign DNA to use for comparisons. Our review showed dried stain samples yielded the most usable profiles when compared to OVRs and underpants. Of the cases where dried stains were submitted, 78% of those cases yielded usable profiles from the dried stain samples. Only 48% of the cases where OVRs were submitted produced usable profiles. Furthermore, 49% of all the CODIS profiles entered from the kits evaluated came from dried stains alone. This study gives compelling evidence that testing samples outside of cavity swabs is beneficial when processing sexual assault collection kits.
Meng-Han will present how trained ANNs can assist laboratories streamline the designation of forensic DNA profiles. They will describe the importance of the training regimen and how performance metrics can be used to validate the ANN and give examples for DNA profiles generated using the PowerPlex® Fusion 6C profiling kit.
Can you give us a sneak peek into the main theme of your presentation and why it’s important for our audience?
DNA profile analysis is a fundamental process which produces the profile data upon which all subsequent DNA interpretation is based on. Recent advancements in machine learning have allowed increased automation and consistency of data processing in many fields of application. We provide an overview of how artificial neural networks (ANN) are implemented within forensic DNA analysis software.
How do you hope your presentation will impact the audience or industry?
To provide a more detailed insight into the use of artificial neural networks for DNA profile analysis and to give a more relatable explanation on how this operates.
Are there any resources or tools you recommend for those interested in learning more about your presentation topic?
There are several publications that describe this topic in detail:
D. Taylor, D. Powers, Teaching artificial intelligence to read electropherograms, Forensic Science International: Genetics 25 (2016) 10-18 https://doi.org/10.1016/j.fsigen.2016.07.013
D. Taylor, A. Harrison, D. Powers, An artificial neural network system to identify alleles in reference electropherograms, Forensic Science International: Genetics 30 (2017) 114-126 https://doi.org/10.1016/j.fsigen.2017.07.002
D. Taylor, M. Kitselaar, D. Powers, The generalisability of artificial neural networks used to classify electrophoretic data produced under different conditions, Forensic Science International: Genetics 38 (2019) 181-184 https://doi.org/10.1016/j.fsigen.2018.10.019
L. Volgin, D. Taylor, J.-A. Bright, M.-H. Lin, Validation of a neural network approach for STR typing to replace human reading, Forensic Science International: Genetics 55 (2021) 102591 https://doi.org/10.1016/j.fsigen.2021.102591
D. Taylor, Using a multi-head, convolutional neural network with data augmentation to improve electropherogram classification performance, Forensic Science International: Genetics 56 (2022) 102605 https://doi.org/10.1016/j.fsigen.2021.102605
When you’re not working, what’s your favorite way to unwind or relax?
Outdoor activities, photography, listen to music, enjoy good coffee.
What were you doing in 1989, when ISHI first started?
No idea. Probably doing what most toddlers would be doing – driving my parents crazy.
Can you share a memorable moment from ISHI that has stayed with you?
This is my first attendance at ISHI.
