Watch Dr. Barash presentation "Unlocking Justice: The AI Revolution in Forensic Science" at the Human Identification Solutions (HIDS) 2024 online conference: https://www.thermofisher.com/us/en/home/about-us/events/life-science/hids.html or via direct link: https://drive.google.com/file/d/1-yJBTLrsOnPsI1quu7oVhSEym3SBqlBP/view?usp=sharing 

Environmental DNA (eDNA) is transforming ecological and forensic studies by providing non-invasive methods to detect and monitor trace genetic material from various sources. This research proposal explores the potential of using car cabin filters as a novel source of forensic evidence. By investigating the persistence and recovery of human and microbial DNA from these media, the study aims to enhance forensic investigation techniques, especially for cold cases. The project employs state-of-the-art DNA extraction and sequencing technologies to analyze eDNA captured in vehicle interiors. Preliminary results demonstrate that biological material can be retained in car air filters, yielding forensically informative STR profiles that can be matched to vehicle occupants. This approach can provide valuable insights into indirect DNA transfer mechanisms, including vehicle occupants' identities and presence durations, offering a new dimension to crime scene investigation.

Biological traces left on objects through handling can undergo a series of transfers, where they move from one object to another, often involving intermediary individuals or objects. Despite the critical role of understanding how DNA is deposited on objects or persons in legal trials, the complex landscape of indirect DNA transfer scenarios remains largely elusive.

In line with the importance of better understanding the dynamics of DNA transfer, this study explores the possibility of DNA retention in the machine and dryer drums and subsequent transfer onto the next load. The study involved swabbing the drums of 100 public washing machines and 50 dryers. Additionally, 60 samples were collected from 20 new unworn socks individually washed in 20 public washing machines, and from 10 socks dried in 10 public dryers. The samples collected in both experiments were extracted, quantified, and genotyped for a standard set of STR markers.

Results revealed amplifiable DNA in 30% of washing machine drums and 14% of dryer drums, with a concentration ranging between 0.013ng/ul and 2.76 ng/ul. Surprisingly, over half of the genotyped samples resulted in a single source profile or simple mixtures with a major profile, suitable for statistical interpretation and inclusion in a DNA database. In the DNA transfer experiment, 21 samples from washing cycles and 8 samples from drying cycles yielded DNA between 0.04 ng/ul and 0.41 ng/ul, currently awaiting genotyping.

This study confirms DNA can persist in washing machines and dryers, potentially transferring to subsequent loads, highlighting the risk of detecting unrelated and misleading traces. Therefore, caution is essential when assessing DNA profiles from garments.

The main aim of this project is to evaluate the genotyping success from challenging biological samples with the RapidHIT ID (Thermo Fisher Scientific) instrument. This novel platform has previously been evaluated with blood, saliva and tissue samples. However, there is a very limited number of studies on testing genotyping success with challenging DNA samples, such as fired casings and other types of trace DNA evidence.

Our research group is exploring how affordable laboratory automation, using the Opentrons 2 (OT-2) robotic system, can enhance forensic DNA profiling. This ongoing study focuses on integrating automated liquid handling and customized programming to significantly reduce errors, improve efficiency, and increase reliability at a lower cost than traditional automation systems.

The OT-2, known for its precision, open-source design, and user-friendly interface, has been optimized specifically for forensic DNA workflows, including DNA extraction with PrepFiler™ BTA and amplification using the GlobalFiler™ system. Although initial calibration issues presented challenges, systematic troubleshooting and adjustments have greatly improved the robot’s performance and reproducibility.

Early results show the OT-2 effectively streamlines forensic DNA processes, maintaining accuracy and consistency. Future work includes further automation of complex protocols such as next-generation sequencing library preparations, highlighting the significant potential of cost-effective robotic solutions in forensic science.