An 84-year-old man was arrested for an unsolved murder from 50 years ago after being linked to the crime through genetic genealogy, authorities said Monday.

The Dunn County Sheriff’s Office said that on February 15, 1974, Mary Schlais was found stabbed to death on a road in Dunn County, Wisconsin, about 75 miles east of Minneapolis.

Schlais, a successful artist, is believed to have been hitchhiking from his hometown of Minneapolis to an art exhibit in Chicago when he was killed, authorities said.

Decades passed without an arrest.

A sock hat, a key piece of evidence, was left at the scene, but the hairs on the hat had no match in the Combined DNA Index System, a law enforcement database known as CODIS, according to the sheriff’s office.

Then last year, the Dunn County Sheriff’s Office partnered with Ramapo College of New Jersey to try to solve the case using investigative genetic genealogy.

With genetic genealogyAn unknown killer’s DNA at the crime scene can be determined through family members who voluntarily submit their DNA to genealogy databases. This allows police to build a much larger family tree than using law enforcement databases such as CODIS.

Authorities said a possible family lineage of the suspect was identified in the fall of 2023.

An investigation was launched this January into a person possibly connected to the suspect, and in May police interviewed that person at his home in Wyoming, authorities said.

Investigators determined the man was not a suspect but directed police to another possible suspect, his cousin in Michigan, authorities said. Authorities said the man in Michigan was also interviewed and determined not to be a suspect, “which exhausts all known male family members in this family lineage.”

Authorities later said they were considering the possibility that the mystery suspect was adopted and therefore unknown to people in his family tree.

This fall, researchers spoke with another relative who agreed to use her genetic profile to help, authorities said. That relative led to the suspect, 84-year-old Jon Miller, whose DNA was linked to the crime scene, authorities said.

Police determined Miller’s DNA was a match on Nov. 4, Schlais’ 76th birthday.

Miller, who was adopted, was arrested for murder Thursday at his home in Owatonna, Minnesota, authorities said. Miller confirmed his involvement in the murder when confronted with the evidence against him, according to sheriff’s officials.

“As soon as he opened the door, he let us know that he knew why we were there,” authorities said.