84-year-old charged in 1974 cold case murder of hitchhiker thanks to DNA from hat left at scene

The cold case killing of a Wisconsin hitchhiker has been solved 50 years later thanks to a DNA breakthrough from evidence pulled from a hat that the accused killer left behind at the scene.

Jon Keith Miller, 84, was arrested Thursday after he “confirmed his involvement” in the vicious stabbing of Mary Schlais, whose body was found at a Spring Brook intersection in February 1974.

Schlais, just 25, had been hitchhiking to a Chicago art show when she turned up dead that cold morning, and investigators were left with few leads beyond one piece of possible evidence — a stocking cap found near her body, from which a few hairs were pulled.

But for 50 years, there was little police could do with them until the Dunn County Sheriff’s Office teamed up with the genetic genealogy department at Ramapo College in New Jersey, CBS News reported.

Investigators were able to use the hairs to create a genetic profile, and from there identified potential relatives.

That process led to Miller’s daughter, which then positively connected the hairs’ DNA to him.

When police interviewed Miller, who now lives in Minnesota, on Thursday, he initially denied knowing anything about the murder — but once presented with the DNA evidence he fessed up.

The grizzled octogenarian said he saw Schlais hitchhiking on the side of the road that night and picked her up, according to the criminal complaint from his arrest cited by CBS News.

After driving off, he started asking her for “sexual contact” — but when she refused, he pulled out a knife and began stabbing her in the back, slashing away as she tried to defend herself, per the complaint.

He then pulled over and began hiding her body in a snowbank, but when a car drove by, he panicked and took off — leaving behind the hat that would implicate him five decades later.

“When he went by the guy was just staring at him. He said he’ll never forget the look on his face,” said Mary Dodge, whose neighbor Denny Anderson was the man who drove by and scared Miller off, CBS News reported.

Police said Miller was “fairly calm about what had occurred” when he confessed.

“I believe it’s got to even be a relief for him after 50 years of living with this. It’s had to have been on his mind almost every day,” Dunn County Sheriff Kevin Bygd told reporters Friday, according to CNN.

“You would think anybody with a conscience, it would. So, I think he was done fighting it, personally.”

Bygd called the arrest “a huge victory for our agency,” explaining how decades of officers assigned to the cold case routinely came up empty-handed — and that without Ramapo College’s help, that might have remained the case.

“Agencies can spend thousands and thousands of dollars sending DNA samples to private labs across the country to try and get results, and we had a college very willing to step up and help us with this process,” he said.

Before Miller was implicated, for years the prime suspect in Schlais’ murder was Randall Woodfield — who was briefly a member of the Green Bay Packers, but was later sent to prison for murder. He is suspected of being the “I-5 Killer,” who had numerous victims across the 1980s.