Police turn to new DNA-powered technology in hopes of finding killer

Posted: Published on February 24th, 2015

This post was added by Dr P. Richardson

By Melody Schreiber February 23 at 2:57 PM

Four years ago, Candra Alston and her 3-year-old daughter, Malaysia Boykin, were murdered inside their South Carolina apartment. Police in Columbia collected DNA at the scene, but the investigation stalled.

Prime-time crime shows would have you believe DNA samples can convict the guilty and clear the innocent, but real life is more complicated. In order to find an assailant, the DNA has to match either a previous offender in the FBIs CODIS database or a sample from one of the victims acquaintances. When it doesnt, the investigation hits a wall. In the South Carolina case, police gathered 150 DNA samples and conducted 200 interviews with likely suspects and still nothing.

Now the Columbia police are experimenting with a new technology that uses tiny amounts of DNA to create a computer-generated illustration of their suspect. Snapshot, a program developed by a Reston, Va., company called Parabon NanoLabs, goes beyond simply listing physical attributes eye color, hair color, ethnicity and facial features and creates a 3-D image of what the killer might look like. The police in South Carolina hope that publicly releasing the suspects image and description will bring up fresh leads in a stale case.

Dabrien Dabe Murphy, the senior solutions architect at Parabon, sits in front of three monitors in a little office on the fourth floor of an unremarkable Reston office building not exactly the first place that comes to mind when you think of a lab. With a few keystrokes, Murphy brings up a revolving 3-D image the back of a head. Another few taps and a face attaches itself along the hairline. The face is a mans: olive skin, greenish eyes, full lips.

Murphy has fed DNA markers, linked to certain facial attributes, into 3-D imaging software to create what he calls a composition. It produces a somewhat distorted image where the face meets the rest of the 3-D model.

Theres a little bit of, okay, manual manipulation to make this not look quite so Frankensteined, Murphy explains. Using his cursor to adjust points and axes in the imaging software, Murphy smooths out the hairline and jaw where the projected face attaches itself to the head.

According to the markers Murphy feeds into the imaging software, the man on the screen is of Northwest African ancestry, with hazel or green eyes; black or brown hair; and few or no freckles. This mans DNA was publicly available, so theyre using it to test their model; they know, from the data included with the DNA, that he is Algerian. The trait predictions come with varying levels of confidence; Parabons scientists are 73.4 percent sure that their skin color prediction is accurate, but they are 94.7 percent confident in the subjects eye color.

All this from 9.6 nanograms of DNA. Thats less than 0.00000001 grams, an amount so small, its hard to compare to anything else.

Snapshot combs through a genotype, searching for significant markers and clusters that might indicate physical attributes and removing unimportant variables.

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Police turn to new DNA-powered technology in hopes of finding killer

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