Today’s sponsored guest blog is written by Bode Technology.
What is FIGG?
Forensic Investigative Genetic Genealogy (FIGG) pairs advanced genotyping technologies with traditional genealogical research to provide investigative leads for unknown DNA evidence when CODIS searching is unproductive. It gained worldwide attention as an investigative tool after the 2018 arrest of the suspected Golden State Killer, Joseph DeAngelo. Since then, it has been used to resolve hundreds of cold cases and has become a time-efficient method for identifying missing persons and perpetrators of violent crimes. FIGG’s success in resolving high-profile cases has led to a surge in inquiries from investigators interested in FIGG for cold cases. However, the forensic community has identified the need for further development, assessment, and evaluation of FIGG procedures to establish best practices.
Our Current Research:
Comparative Evaluation of Genotyping Technologies for FIGG in Sexual Assault Casework
Development of best practices must start with a systematic evaluation of the technologies used to generate high-density single nucleotide polymorphism (SNP) genotypes. These technologies were developed and validated with pristine samples intended for use in clinical genomics, whereas forensic samples can contain low-template, degraded, and biologically contaminated DNA.
Our work evaluated how low-template DNA and degradation affect the quality, accuracy, and reproducibility of SNP genotypes and how this affects genealogical database searching and identification of potential relatives. Three genotyping technologies were investigated: SNP microarray testing with Illumina’s Global Screening Array v2 BeadChip (array), whole genome sequencing (WGS) on the NovaSeq 6000, and targeted sequencing with Qiagen’s ForenSeq Kintelligence Kit on the MiSeq FGx. All technologies were sensitive to low-level DNA inputs. For UV-degraded samples, increased degradation adversely affected call rates for both array and WGS, whereas Kintelligence call rates were robust against degradation. While genotype concordance was negatively impacted for array, WGS and Kintelligence demonstrated high concordance, regardless of the amount of degradation.
The resulting SNP genotypes were compared against genotypes in GEDmatch to determine the maximum distance at which genealogical associations could be identified. For all technologies, robust matching was observed out to the 2nd cousin level with low-level DNA inputs. Slight to significant degradation had minimal impact on 2nd cousin matching for Kintelligence and WGS, while moderate degradation significantly impacted 2nd cousin matching from array samples. Anomalous results were observed with the WGS SNP set of >2 million loci or donors of non-European ancestry, and inconsistencies were observed in genotypes generated with Kintelligence when compared to array and WGS. Kintelligence also displayed limited utility due to its incompatibility with third-party comparison tools.
The limitations of each technology will be further tested by examining low-level and degraded samples using a donor with family members of known relationship distance greater than 5th degree in GEDmatch. After genotyping, a full genealogical investigative workflow will be applied to demonstrate whether increasingly distant relatives can be identified and at what distance identification is no longer possible. Workflows for each technology will also be compared for range and accuracy.
Our goal is to help FIGG practitioners make more informed decisions, optimize resources, and enhance investigative outcomes. Additionally, this work may support the development of new genealogical workflows for samples that generate suboptimal results. Such analyses empower forensic experts to select the most effective methods tailored to specific cases, accelerating the identification of suspects and resolution of cases.
This project is supported by Award No. 15PNIJ-21-GG-04143-MUMU, awarded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect those of the Department of Justice.
Improving FIGG for Challenging Forensic Samples
FIGG has also become critical for the identification of missing persons and unidentified human remains. With the University of Tennessee Knoxville Forensic Anthropology Center, we are optimizing a workflow for library preparation and target enrichment hybridization capture from compromised bone samples that is amenable to implementation in a standard forensic laboratory. With support under NIJ Award No. 15PNIJ-23-GG-04224-RESS, this project aims to improve sequencing of DNA obtained from compromised bone samples, allowing for more identifications of human remains.
Transitioning to In-House Operations
FIGG presents a unique challenge to forensic laboratories, which are not typically equipped with the sequencing technologies used to generate high-density SNP genotypes. Initially, sequencing was outsourced by sending extracted DNA to third-party laboratories specializing in SNP microarray testing and WGS. However, due to FIGG’s sustained success, practitioners are now considering how to integrate end-to-end FIGG processing into their accredited forensic laboratories.
Leveraging our years of forensic and sequencing experience, Bode has validated two FIGG sequencing methods: the ForenSeq Kintelligence Kit on the MiSeq FGx and WGS on Element Bioscience’s Element AVITI™ System. The AVITI is a short-read, mid-throughput sequencer that uses Element Bioscience’s sequencing-by-binding chemistry to reduce run costs and improve performance when compared to sequencing-by-synthesis chemistry, the current gold standard. AVITI sequencing offers shorter run times and improved base call accuracy and detection, with mean quality scores exceeding Q40 — a 10X improvement on the current benchmark. These innovations make AVITI sequencing ideal for challenging forensic evidence. With this technology, our pipeline now encompasses all steps of the FIGG process: receipt of evidence, sampling, DNA extraction, library preparation, sequencing of SNP genotypes, bioinformatic processing, upload to genealogy databases, genealogical research, and court-ready reporting.
Moving FIGG Forward
Bode is proud to be a leader in the FIGG community. We continue to explore FIGG’s potential, contributing new data to the broader body of FIGG knowledge and pushing our work to the forefront of forensic science. We remain committed to advancing FIGG while ensuring the technology adheres to the standards required for traditional DNA casework methods. Since launching our FIGG service in 2018, Bode has processed over 500 FIGG cases, and 30 cases were processed with our end-to-end FIGG workflow with AVITI sequencing directly following its release. Over 300 investigative leads have resulted from this work, underscoring FIGG’s value to modern forensic investigations. We look forward to the future of FIGG and will continue sharing the results of our FIGG research with the community.
