A man suspected of murdering four college students last November was caught by matching DNA found at the crime scene to a sample provided by a family member on a genealogy testing website.

Investigators had run unidentified genetic material on a knife sheath found at the crime scene through a public database, searching for potential familial matches, according to reporting by AP News, Fox News, and CNN.

As such, Bryan Kohberger, a graduate student of criminology and criminal justice at Washington State University, was identified and tracked by an FBI surveillance team. The 28-year-old was arrested in his native state of Pennsylvania on December 30 and, after being extradited back to Idaho, will make his first appearance before a judge on Thursday.

The genetic match was a major break in the case, which has baffled investigators for weeks.

In the early hours of November 13, Xana Kernodle, 20; Ethan Chapin, 20; Madison Mogen, 21; and Kaylee Goncalves, 21, were brutally murdered in their off-campus apartment, shaking the small college town of Moscow, Idaho, which had not seen a murder in seven years.

Adding to the fear was the grisly nature of the crime itself — they were stabbed repeatedly in their sleep using a fixed-blade Ka-Bar-style knife — and the apparent absence of a suspect or motive. As the weeks went by without any news, those closest to the victims grew increasingly desperate.

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“I have to assume and hope that this is all part of [local law enforcement’s] plan and … they’ve got this all figured out,” Steve Goncalves, Kaylee’s father, had told ABC News. “I have to have my justice. These families deserve that.”

Criminal investigations have been revolutionized by genetic genealogy, a technique for studying family history, by allowing investigators to identify remains or point out a likely perpetrator. Yet at present, according to Forensic Mag, the vast majority of cases solved through genetic genealogy are cold cases.

One reason for this is that few DNA databases work with law enforcement, according to Fox News.

GEDmatch, a genetic genealogy service, allows users to opt-in for their information to be accessible to police but otherwise does not share the information.

FamilyTreeDNA, another service, similarly only shares DNA matches with police if users have opted to participate in its Investigative Genetic Genealogy Matching (IGGM) feature.

Ancestry.com will not provide data to governmental or judicial authorities without being required to do so through a subpoena or warrant.

According to a survey conducted last year by YouGovAmerica, 21% of Americans have taken a mail-in DNA test, and 27% say that a close family member has done so.

While a gag order has been issued for the Idaho student killings case, an affidavit reveals that alongside the DNA evidence, Kohberger owns a white Elantra — the same type of vehicle caught on surveillance footage from the neighborhood around the time of the killings between 3:29 a.m. and 4:20 a.m. The motive remains unknown and a murder weapon has not been found.

Nonetheless, Kohberger’s family maintains that he is innocent.

According to Jason LaBar, chief public defender for Monroe County, who represented Kohberger during his extradition hearing, “They’re obviously shocked. This is certainly completely out of character, the allegations, and really they’re just trying to be supportive with the understanding that these four families have suffered loss.”

If found guilty, Kohberger will face four counts of first-degree murder as well as a felony burglary charge.

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