Interview written and condensed by Mandi S. Van Buren, MS

I have a master’s degree from the University of Florida in Pharmacy with a concentration in forensic drug chemistry and a Bachelor of Science degree from the University of Tampa in biology. My initial career path from a young age was to go to medical school and be a doctor but something in me was pulling me also towards law enforcement. While in my first year of graduate school in a PhD program I heard a speaker from the FBI discussing forensic science and DNA as it applied in her case. That speaker changed my path immediately and I knew then I wanted to be in the forensic science field. I began my career in forensics over 15 years ago at the Utah Bureau of Forensic Services. I worked as a Senior Forensic Scientist primarily in the DNA Unit and cross trained in the controlled substance unit and crime scene response team for over 7 years. I then relocated to California and worked for the Tulare County Sheriff Office as the first civilian Field Evidence Technician with their department focusing on crime scene response. In 2016, I started with the Kern Regional Crime Lab and moved through the ranks until ultimately being promoted to the DNA Technical Lead in 2019. Currently I am working for DNA Labs International as a DNA analyst.

The Kern Regional Crime Laboratory is a full-service laboratory offering an expansive number of forensic services to the law enforcement community. The laboratory serves over 40 agencies across Kern County including local police agencies, numerous prisons, and the local school district. The DNA analysis unit specifically conducts serological testing for body fluid identification, DNA analysis, kinship for criminal paternity cases, familial searching, CODIS, and a complete local database for generation of investigative leads. On average, the DNA unit receives 700 requests for service annually and completes testing of over 2,500 DNA samples. Case submissions are approved for all types of cases including felonies and misdemeanors from homicides and sexual assaults to property crimes. In addition to current casework, the DNA unit received many requests for analysis of evidence related to cold case homicides and sexual assaults.

During the initial considerations of adopting NGS technology, the laboratory was operating with an out-of-date genetic analyzer, limited resources, and an increase of more complex DNA profiles for interpretation with the allowance for touch DNA samples to be submitted for testing. Additionally, the laboratory had Y-STR testing available but, due to the workflow being used, not all evidence items had enough sample available to test both autosomal STRs and Y-STRs, even if the sample was deemed suitable for Y-STR testing.

In 2018, the MiSeq FGx instrument and the ForenSeq DNA Signature Prep kit had been approved by NDIS for use on forensic samples. Since the DNA unit relies primarily on grant funds for equipment and reagents, this approval allowed the lab to use its grant funding to purchase the MiSeq FGx workflow with ForenSeq DNA Signature Prep. We believed the system would alleviate some of our challenges and streamline our current workflow by providing aSTR and Y-STR genetic information in a single amplification reducing analyst time in the lab. Additionally, we hoped for improved mixture deconvolution with the identification of isoalleles with NGS. We utilized probabilistic genotyping for all mixture interpretation for our CE workflow and often an analyst would struggle estimating the number of contributors in a complex mixture. The additional aSTR markers, combined with the availability of Y-STR data, SNP data, and identification of isoalleles would provide analysts with more information to accurately estimate the number of contributors during interpretation.

As with any new technology or instrument, there are always going to be concerns. The decision to implement NGS, I think, came with even more concerns because at that time, no other forensic crime lab had successfully implemented this instrument and testing kit for evidence samples. In addition, we were bringing this technology online with the plan to eventually replace and phase out CE technology in our lab completely. We didn’t know what support we would have from all involved stakeholders including lab management, law enforcement customers, the DA’s office, and technical support from vendors. As the project continued, other considerations arose including data storage and cost, training, and implementation strategy. I was a newly appointed DNA technical lead and was handed this project when the unit was understaffed and dealing with a backlog of cases. I knew my team would not be welcoming this change with open arms as all change slows down the process, adds additional training obligations, and would require more from everyone when our plates were already full.

However, my experiences through this process from validation, implementation, and the admissibility hearing have made me a true supporter of this technology. The amount of knowledge and support we gained overshadowed the initial concerns. By having to face these challenges, I was forced to find answers or troubleshoot issues directly with vendors. I gained more technical knowledge through this validation than any other project I have worked on.

NGS was initially validated to be used on all casework samples, including evidence and known reference items. During implementation, the plan shifted to samples from violent crime cases only. The workflow would be to evaluate samples at quantification and then decide if a whether to use primer set A or B. Some considerations for this decision included how much sample did we have, did we consume the item, is there any potential subjects or are they unknown.

The first 10 cases utilizing NGS were violent crime cases and focused on samples originating from biological fluids. Our interpretation protocol states that all mixtures must be interpreted with probabilistic genotyping software, so our NGS testing was limited until the completion of additional validation projects. Once NGS and probabilistic genotyping validations are fully implemented, all samples of any case type would be acceptable for NGS.