The case was cold for five decades before genetic genealogy experts at Ramapo College looked at DNA from a stocking cap left at the scene.

 A Minnesota man will spend the rest of his life behind bars after pleading "no contest" in court to killing a Minneapolis woman he picked up hitchhiking five decades ago. 

Jon Keith Miller was charged last November with first-degree intentional homicide for the killing of 25-year-old Mary Schlais. She was found dead in the town of Spring Brook, Wisconsin, on February 15, 1974. Miller was 33 at the time. 

The case was cold for five decades despite a stocking cap being left at the scene and a witness seeing Miller's car. The witness misremembered the car's color, leading Miller to believe he "got away with it." 

Miller spoke to KARE 11, admitting to reporter Lou Raguse he wanted to have sex with Schlais and stabbed her when she said no. He said he didn't know his stocking cap was left behind until officers investigating the case showed him a photo of it in 2024. In court Thursday, video was played by the prosecution where Miller told investigators that the photo he was being shown was of his cap. 

The cold case heated up when genetic genealogy experts at Ramapo College looked at DNA from that stocking cap. It's the same method that has been used to solve cold cases across the country since it was famously used to catch the Golden State Killer in 2018. 

Miller told Raguse he planned to plead guilty "because I know I am. Why go through all the mess?" he said. "Put me away for the rest of my life." 

In court on Thursday, Miller was given the opportunity to speak but chose not to. A portion of his interview with KARE 11 was played by the prosecution, when he said he didn't think of the murder much over the past 50 years. 

Schlais was a University of Minnesota honors graduate living in Minneapolis in 1974. She was hitchhiking to Chicago for an art show. Dunn County Sheriff Kevin Bygd said at the November press conference announcing the charges that back then it "wasn't that unusual to hitchhike from Minneapolis to Chicago. But stories like this are the reason we don't let our kids do that anymore."

Family members of Schlais were in court Thursday to watch the verdict.