Lorrie Ann Smith was just 28 years old when she was shot in the back at point-blank range in the bedroom of her southern Fulton County home in Georgia on May 25, 1997.

There was no sign of sexual assault or robbery, according to news reports, but there was plenty of evidence that Smith struggled with her killer, who left fingerprints and droplets of blood in the home, which she shared with her parents. Her father found her body when he went into her bedroom to wake her up to go to church the morning after the murder.

DNA profiling in criminal cases wasn’t standardized in U.S. investigations until 2004, when President George W. Bush signed the Justice for All Act, and the local Fulton County police soon hit a dead end when they couldn’t find any matches in their local database to the forensic evidence they collected from the crime scene. Smith’s murder was soon marked unsolved, and the criminal dossier was filed away until this summer, when a Fulton County detective decided to use a private DNA testing company on a number of their cold cases to try to bring closure to the victims’ families, including Smith’s two-decade-old homicide.

The new investigation led to the arrest this week of 61-year-old Jerry Lee, a married father who was a corrections officer in Atlanta at the time he allegedly murdered Smith, who was a multilingual marketing specialist who served as a youth counselor at the Union Christian Church of College Park, according to the Fulton County Police Department. Smith’s mother Jean told a local television station that he had lived next door. “He was a heartless killer,” she told WSB-TV. “The biggest question is: Why did he do it?”

The Fulton County cops used Parabon NanoLabs, which is a private company that scans public DNA profile records submitted through genealogy searches meant to help people find lost relatives. Increasingly, these records have been used to help solve historical crimes. Parabon has been involved in solving a number of criminal cold cases, according to its website, including the recent arrest of the Golden State Killer.

Genetic companies like Parabon NanoLabs say they don’t have access to private criminal or immigration records collected by police. Instead, they tap into public records that are generated when people engage in genealogy searches through companies like Ancestry.com to try to match DNA collected at crime scenes. In the case that led to Smith’s murderer, Lee’s distant cousin had been tracing his family tree and had provided his own DNA for matching to any relatives also making similar searches, according to a report by WSB-TV in Atlanta.

When the DNA from Smith’s crime scene was cross-referenced on the global public database, the geneticists found similarities in the DNA strain provided by Lee’s cousin. Police then used traditional investigative techniques to determine who among the curious cousin’s relatives might have been in southern Fulton County, Georgia, back in 1997. Those investigations led them to Lee. Police then obtained a search warrant in Alabama, where Lee was living, to take a DNA sample. Only then were they reportedly able to make an exact match that led to Lee’s arrest this week in a hotel room, where he was staying with his wife.

Smith’s family issued a statement through the Fulton County Police Department. “We have some relief,” they said. “One chapter has closed, but there are new ones opening with trials, sentencing and all that we will be learning about the next phase of the process.”

Twanesa Howard, the Fulton County Police Department detective in charge of cracking this case, told the local television station she was relieved: “It feels wonderful to finally bring some kind of closure to this family.”