For seven years, investigators have searched for a killer and a motive in the fatal stabbing of a South Salt Lake bookseller.

On Thursday — the seven-year anniversary of 64-year-old Sherry Black’s death — South Salt Lake police Chief Jack Carruth said “advanced DNA information” has helped them figure out what the man who fatally stabbed Black may have looked like.

He is an African-American with light brown to brown skin and black hair, police said.

Using a technology called phenotyping, a lab in Virginia created images of what the man may have looked like based on genetic code that dictates physical traits, such as face shape, and eye, skin and hair color.

Not knowing the man’s age, the lab, Parabon Nanolabs, created images of what he would look like at ages 25, 38 and 52.

(Trent Nelson | The Salt Lake Tribune) A portrait of Sherry Black along with DNA based snapshots of a suspect at various ages on display at a news conference where South Salt Lake police released the new DNA portrait in the cold case slaying of Sherry Black, who was stabbed to death seven years ago. Thursday November 30, 2017 in South Salt Lake.

The DNA evidence doesn’t account for weight, hairstyle or other environmental factors, but it does indicate ancestry and other physical traits, police said.

Some researchers are skeptical of the new technology. Yaniv Erlich, a Columbia University computer science professor who studies genetics, told The New York Times in October that the idea of using DNA to create a facial mock-up of a suspect is “on the verge of science fiction.”

Part of the skepticism is because Parabon hasn’t offered up its method for peer review and the scrutiny of researchers.

Parabon Nanolabs combined the attributes gleaned from the DNA evidence into the composite images. The images were released with various confidence levels. For example, the company is 99.6 percent confident that the suspect has black hair, and it is 75.4 percent confident that he has zero or few freckles.

The lab also predicted that the killer has a larger than average brow, eyelids, nose and upper lip, based on the genetic code in the DNA.

But some scientists say the interaction of genes and facial features is far from being fully understood. Manfred Kayser, a professor of forensic molecular biology at Erasmus University in Rotterdam, Netherlands, told NBC in July that trying to predict the nuances of someone’s face based on DNA is not reliable, and that the science is in its infancy.

The technology was launched in 2015, according to police. This case marks the first time it has been used in Utah, but it has been used in other states.

“It’s becoming the industry standard,” South Salt Lake police spokesman Gary Keller said. “They use it a lot for found human remains.”

Keller said he isn’t worried that the technology could be misused.

“Would we arrest anybody just based on that photo and the resemblance? No,” Keller said. “There would be a lot more investigation.”

Bridget Algee-Hewitt, a research scientist at Stanford University, told Cell, a scientific journal, that information in the hands of police could be misunderstood — someone of “African origin” could be labeled as “African American.” She said it had potential to instigate “racial profiling at its worst.”

The victim’s family also announced Thursday they are raising the reward amount from $50,000 to $250,000.

On Nov. 30, 2010, Black was beaten and stabbed at the bookstore she ran with her husband, B&W Billiards and Books, at 3466 S. 700 East. The door hadn’t been forced open, police said, and there was no indication that anything was missing from the store. There was money in the cash register.

Sherry Black was murdered in her South Salt Lake home and book shop on Nov. 30, 2010.

Earl Black found his wife’s body that afternoon.

On Thursday, Earl Black, his daughter, Heidi Miller, and his son-in-law, Greg Miller, returned to the bookstore for the announcement of the DNA development. They said they hoped the additional information — as well as the increased reward — would spark a lead.

“I believe that people who know something about this crime will see the information that’s distributed today,” Greg Miller said. “On behalf of the family, I would implore you to come forward and share what you know so we can catch the person that killed Sherry before he can hurt somebody else.”

The family closed the bookstore and sold the property four or five years ago, Greg Miller said. The bookstore reopened as a photo studio.

“It’s too painful to live here,” Heidi Miller said of her father’s decision to sell the property, where Sherry Black and her husband also lived. “Too many memories — good and bad memories.”

Although police have not had a suspect in the past seven years, they said it has never been considered a cold case.

Rick Egan | The Salt Lake Tribune Greg and Heidi Miller announce the establishment of the Sherry Black Education Foundation at a media conference at the Calvin L. Rampton Complex, Tuesday, May 30, 2017.

The killer left some blood behind after the stabbing; police believe the man cut his hand while stabbing Black. His DNA was entered into the FBI’s national database, the Combined DNA Index System, but there has been no match, police said.

Investigators then tried more advanced DNA techniques. Detectives used a process called familial DNA testing, which also came back without answers. Then, the police turned to Parabon Nanolabs.

Over the years, Sherry Black’s family created a website, offered a reward and posted her photo on billboards in an effort to find her assailant.

A prominent detective squad called the Vidocq Society — a Philadelphia-based group that examines unsolved crimes — came to Utah in 2012 to help South Salt Lake police.

“The person who killed her is still out there, and it has been way too long. We need to catch that person and put him away so he can’t hurt anybody else,” Heidi Miller said Thursday. “You know anything, no matter how small a detail is to you, please call our tip line at 801-412-3688.”