Models of a criminal's face may so be generated from any trace of DNA left at the scene of a crime. Computer-generated 3D maps will show exactly how the suspect would have looked from an angle.

Mark Shriver of Pennsylvania State University and his team developed the application, which produces a virtual mug shot of potential criminals.

Shriver and his team took 3D images of almost 600 volunteers, coming from a wide range of racial and ethnic groups. They superimposed more than 7,000 digital points of reference on the facial features and recorded the exact position of each of those markers. These grids were used to measure how the facial features of a subject differ from the norm. For instance, they would quantify the distance between the eyes of a subject, and record how much more narrow or wide they were than average.

A computer model was created to see how facial features were affected by sex, genes and race. Each of the study participants were tested for 76 genetic variants that cause facial mutations. Once corrected for race and sex, 20 genes with 24 variants appeared to reliably predict facial shape.

"Results on a set of 20 genes showing significant effects on facial features provide support for this approach as a novel means to identify genes affecting normal-range facial features and for approximating the appearance of a face from genetic markers," the researchers wrote in the article announcing the results.

As part of data collection, the team asked participants to rate faces based on perceived ethnicity, as well as gender.

Digital facial reconstructions from DNA have proven to be notoriously unreliable. Even seemingly simple information like height can be difficult to determine through genetic analysis. Other aspects of human physiology, such as eye color, are easier to predict using genetic analysis.

"One thing we're certain of [is] there's no single gene that suddenly makes your nose big or small," Kun Tang, from the Shanghai Institutes for Biological Sciences in China, said.

In order to further refine the system, Shriver has already started sampling more people. Adding further diversity to the database should allow the application to make even more accurate recreations of a person's face. In the next round of testing, 30,000 different points will be used instead of 7,000. Merging this development with 3D printers would make it possible to print out 3D models of a person, just based on a piece of DNA.

Such models - digital or physical - are not likely to be used in courts anytime soon. A more likely scenario is use as modern day version of police sketches, assisting police in finding suspects. Only after an arrest would the DNA of a suspect be compared to that collected at the scene of a crime.

Creating 3D facial models from genetic evidence was detailed in Nature.