DNA on a coffee cup has linked a Michigan businessman to a pair of decades-old rapes on golf courses – including one on the Penn State University campus, authorities announced.

Kurt Alan Rillema, 51, of West Bloomfield, is charged with sexually assaulting a woman at the Twin Lakes Golf Club in 1999 in Oakland Charter Township and a jogger on a Penn State University golf course in 2000.

In the first incident, Rillema allegedly attacked a woman working at a food stand on the course.

"An unknown man came through the back employer door, demanded she take off her clothes and then sexually assaulted her," according to a press release from Oakland County Sheriff Michael Bouchard.

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Kurt Alan Rillema

Kurt Alan Rillema was charged last week in a pair of decades-old rapes on two golf courses in separate states – including Penn State University, right. (Oakland County Sheriff's Office | Google)

Nine months later, on July 27, Rillema allegedly struck again, asking a 19-year-old woman who was jogging near the 18th hole of the Blue Course at Penn State University in State College, Pennsylvania, for a Band-Aid and whether she knew the way to the clubhouse.

When she tried to leave, he allegedly held a knife to her throat and dragged her into the woods, punched her in the stomach and raped her, according to court papers cited by Law&Crime.

Authorities obtained DNA evidence from both rapes, which were uploaded to the Combined DNA Index System, but there was no hit to a suspect.

Kurt Alan Rillema allegedy raped a woman at the Penn State University

Walker Clubhouse, left, and a Penn State University golf course. (Google Maps)

In July 2021, the sheriff's office and Penn State police collaborated on the cold cases and decided to giving cutting-edge DNA technology a try. They sent evidence to Parabon Nanolabs for genetic genealogy testing.

The discipline combines genetic analysis and genealogical research to find matches in public databases.

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Once a DNA sample's related family members are identified, public data and other clues are used to build family trees.

In the case of Rillema, DNA investigators started with distant relatives from the 1700s and eventually narrowed the potential pool of suspects to three brothers.

Twin Lakes Golf Club

Twin Lakes Golf Club in Michigan. (Google Maps)

Investigators quickly zeroed in on Rillema because he lived near the Twin Lakes Golf Club and his brother was attending Penn State at the time of the second rape, according to court papers.

Authorities began surveilling Rillema and obtained a discarded coffee cup with a sample of his DNA earlier this year.

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It matched the DNA left by the perpetrator in both rapes, Centre County First Assistant District Attorney Sean McGraw said at a press conference to announce the charges in Pennsylvania.

Bouchard said Rillema, who owns his own construction business, has no prior criminal record.

"He's an avid golfer and apparently plays golf all over the country," the sheriff added, saying there could be other victims out there.

In Michigan, Rillema has been charged with first- and second-degree felony criminal sexual conduct.

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In Pennsylvania, Rillema will be charged with felony counts of rape, sexual assault and aggravated indecent assault.

If convicted of the top charge, he faces up to life in prison. He's being held without bond.