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raditionally, when DNA samples col- lected from a crime scene did not match either the DNA of a potential suspect or samples from vari- ous law enforcement databases, it would mean a setback for the investigation and potentially a dead end for the DNA evidence.
With recent advancements in next-generation se- quencing, however, the investigation does not need to end there. One of the most important scientific break- throughs in forensics in the last 20 years could lead to a way to unlock biological clues and indicators within complex DNA samples that were previously hidden. The Human Genome Project, which was completed in
2003, identifi ed thousands of biomarkers applicable to DNA-based forensics. With this important discovery, the National Institute of Justice saw an immediate opportunity for applications within law enforcement. Currently, foren- sic analysts can use some simple analysis to match a known suspect’s DNA to the biological samples found at the scene of a crime, but extrapolating that same sample to the larger population is much more challenging.
To further develop this technology for law enforce-
ment, the NIJ issued a grant to the Battelle Memorial Institute, the world’s largest independent research nonprofit. In 2014, Battelle developed ExactID™, the first commercially available software tool designed spe- cifically for the analysis of next-generation sequencing (NGS) data. With the help of this grant, Battelle will be able to further develop tools that use NGS to unpack the complex clues found within DNA evidence. NGS technology takes DNA analysis one step further, allowing law enforcement to draw important conclusions from the analysis of a single “unmatched” DNA sample. The new DNA sequencing and bioinformatics technologies are transforming DNA into an informative and scientifi cally reliable crime scene witness. With this technology, law en- forcement will soon be able to evaluate a series of biomark- ers found in the evidence and predict important physical and ancestral characteristics to support an investigation. What exactly does this research mean for law enforce- ment? Take this example: Detectives are investigating a crime scene where they haven’t yet identified a suspect. The investigators, however, were able to identify a small DNA sample, maybe from a stray piece of hair, a dis- carded cigarette, or an empty beer can. They cross test this sample against their database, the FBI’s database, and their list of suspects, but their search doesn’t turn up any positive results. Previously, this would mean the DNA marks a dead end for the search for a suspect.
Up to this point, forensic DNA analysis methods have cen- tered on matching DNA profiles from a crime scene against DNA profiles of convicted offenders previously entered into law enforcement databases such as the FBI’s CODIS database or the UK’s NDAD database. The idea would be to find out if the perpetrator of the crime is already known to police from previous crimes. Under that paradigm, if the crime scene DNA profile does not match any DNA profile already in the data- base, then little else can be learned from the DNA that helps the investigation.
But now, using this new technology, DNA can help identify suspects by revealing information about the physical appear- ance and ancestral heritage of the DNA source recovered from the evidence. Some clues are similar to what an eyewitness can provide, but in many ways DNA evidence is more objective and reliable, and often more credible in court. This is possible due to the massive increase in biomarker sequencing throughput, which creates both a tremendous op- portunity and a potential problem. The new sequencing tech- nology has yielded the ability to research previously unknown aspects of the human genome, but also has had the unintended consequence of ballooning the complexity and cost of ana- lyzing sequence data. The time and cost limitations in DNA analysis quickly switched from the sequencing process itself
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