Without ever seeing the suspect, new technology is helping Valley law enforcement agencies catch dangerous criminals.

“Biological data is really complex -- there's tons and tons of information in DNA,” said Ellen McRae Greytak is the director of bioinformatics for Parabon NanoLabs.

Parabon NanoLabs is a DNA technology company that specializes in DNA phenotyping, which is the process of predicting physical appearance and ancestry from unidentified DNA evidence.

“We're not identifying a person,” Greytak said. “We're helping narrow down who it could possibly be.”

This week, the Mesa Police Department released an image similar to a composite sketch of a man wanted in connection to the sexual assault of a 4-year-old.

It’s one of a list of law enforcement agencies turning to DNA phenotyping to help advance cases that appeared to have reached dead ends.

“A lot of times these investigators are going into these cases knowing nothing about this person,” Greytak told 12 News.

“We give them predictions, here's the eye color, here's the ancestry, here's the face shape and you can use all of that to eliminate certain suspects,” she said.

They used a DNA sample to predict all that information.

In a traditional police composite, a sketch artist uses eyewitness accounts to piece together what a person looks like.

To create one of these DNA snapshots, scientists analyze an unknown person's DNA sample, then identify markers linked to physical appearance and then compare them to a database of known people to mathematically predict the unknown person’s physical traits.

“The goal is to resemble that person,” Greytak said. “Things like hair, weight and hair style are not in the DNA.”

Scientists turn to sketch artists who can use a library of hairstyles to pick a hairstyle that likely relates to the person.

When comparing DNA snapshots created by Parabon to a picture of the real person, you can definitely see the resemblance.

Scientists are now already working on new technology to take it even further.

“We're hoping to add more traits like straight versus curly hair, is this person likely to go bald early, things like that, which we can later add in," Greytak said.