Genetic genealogy, in which DNA samples are used to find relatives of suspects and eventually the suspects themselves, has led to a first conviction in a cold case, leading some experts to say it has set an important precedent for the use of forensic science.

“There is no stopping genetic genealogy now,” said CeCe Moore, a genetic genealogist whose work led to the arrest in a 1987 murder case, the New York Times reports.

“I think it will become a regular, accepted part of law enforcement investigations.”

On Friday, the jury returned a guilty verdict against William Talbott II in the 1987 murder of a young Canadian couple.

Detective James Scharf of the Snohomish County, WA., Sheriff’s Office took six minutes on the stand to describe how a semen sample collected from one of the victim’s clothing led to two second cousins of the suspect, and then to the man on trial.

The practice had never been tested in court.

While the defense could have challenged the use of genetic genealogy on privacy grounds, or as a violation of people’s right to control their data, Talbott’s lawyers did not pose any question about the technique. They said they viewed genetic genealogy as just another way of generating investigative leads.

“Police have always used a variety of things to develop tips,” said public defender Rachel Forde.

Still, the case was not likely to put to rest a debate over the ethics of using the technique to solve crimes and how to balance privacy with the demands of law enforcement.

Worries about privacy have already led one of the country’s main commercial genealogy services, GEDmatch, to put its DNA database off limits to police.

The company has changed all its profiles to the “opt out” mode, meaning police have access to only those profiles whose users logged on and voluntarily selected to “opt in” and share their DNA.

In the most celebrated case involving genetic matching, police arrested a suspect accused of being responsible for a trail of murders in California, dubbed the “Golden Gate Killer.”

In a paper warning of the growing dangers to privacy represented by authorities’ use of “forensic genealogy,” Stanford Law School researcher Joseph Zabel said the technology needed to be carefully reviewed.

“As technology progresses, and matches from relatives more and more distant are able to be made, the number of individuals who could be subjected to suspicion will grow,” Zabel wrote, striking a theme that evoked dystopian Sci-Fi novels and films.

“If investigators go back far enough, they will find that there is a killer inside all of us.”