Last month, Columbia, S.C., Chief of Police, Skip Holbrook, announced his department was releasing a computer-generated image of a person of interest in a double murder. The image was produced using a new DNA phenotyping service called Snapshot from Parabon NanoLabs.
Snapshot was developed with funding from the Department of Defense by combining a massive catalog of single nucleotide polymorphisms (SNPs) from thousands of willing subjects with a lot of data mining know-how and high-end computing power. A SNP ("snip") is a change in the DNA sequence that can determine variation of physical traits within a species; for example, the difference in humans between blue and brown eyes. Parabon's DNA scientists and computer technologists have identified the SNPs responsible for such traits and for more subtle aspects of a person's appearance and ancestry.
"A copy of this 'DNA blueprint' exists in every cell of the body, which makes DNA a potentially invaluable source of investigative information," says Ellen McRae Greytak, Ph.D., Parabon's director of bioinformatics. "However, traditional DNA forensic analysis treats DNA as simply a biometric identifier, a 'DNA fingerprint' for matching to a known individual."
Greytak says there are two major law enforcement applications for Snapshot: narrowing down a suspect pool in cases where there are no witnesses and no traditional DNA matches and putting a face on unidentified remains.
Parabon's founder and CEO Steven Armentrout, Ph.D., says Snapshot presents law enforcement with an entirely new way to use DNA analysis. "Heretofore, DNA hasn't been used much as an investigative tool; it's brought in at the end of an investigation for the final ID of the suspect. Snapshot moves DNA analysis to the front of an investigation, which saves both time and money."
Snapshot does much more than reveal an unknown subject's hair color and eye color. It can also be used to determine a subject's ancestry in detail.
One of the stages of Snapshot's development was a validation protocol that was used to test its mathematical models. Potential clients were asked to send Parabon samples of DNA from people unknown to the testers.
Greytak says the validation tests have been very successful and have also shown the value Snapshot offers to investigators. During one of the validation tests, Snapshot revealed the person's ancestry was 50% East Asian, 40% Native American, and 10% European, and detailed analysis determined that the subject's mother was Mexican-American and his father was Japanese. "In a real investigation that result could really narrow your suspect pool," Greytak says.
Once a law enforcement agency contracts with Parabon for the Snapshot service, it sends evidence or extracted DNA to one of Parabon's partner labs, which performs processing to determine the SNP sequences. These sequences are then processed using Parabon's prediction models. The client agency then receives a detailed analysis of the physical characteristics and ancestral background of the subject, including confidence levels for each prediction and a list of characteristics that can be excluded with high confidence. With this information, investigators can streamline their investigation by excluding a wide range of individuals from the suspect pool and focus on the most likely suspects.
Snapshot is available now, and Armentrout says the company is receiving a great response from its potential law enforcement clients. "The big thing we want the law enforcement community to understand is that this is a completely different way to use DNA," he says.