Menomonee Falls cold cases, DNA offers answers decades later

MENOMONEE FALLS, Wis. - Investigators are again looking into two decades-old Menomonee Falls cold cases after DNA has offered answers from beyond the grave.

Detectives stood and watched as workers at Milwaukee's Holy Cross pulled a casket from the ground this July. Undisturbed for 15 years, investigators were looking for what was inside: DNA from the body of Clarence Marcus Tappendorf.

Menomonee Falls is now a village home to about 40,000 people. In the 1960s, its population was growing and so were businesses. It is a local union hall now, but in 1966 a building housed Kenworth Manufacturing.

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That's where 19-year-old Diane Olkwitz worked and was found stabbed more than 100 times on Nov. 3, 1966 – her clothes disheveled. It was the village's first homicide, but the case went cold.

Less than five years later, the body of 15-year-old Terri Erdmann was found in a wooded area off Appleton Avenue near the Little Menomonee River. She was nude from the waist down, bound with twine and stabbed roughly 20 times. That case, too, went cold.

Clarence Marcus Tappendorf pulled from Holy Cross cemetery in cold case investigation

That changed in 2001, when court filings say male DNA was found on Olkwitz's undergarments. In 2011, male DNA was found on Terri Erdmann. And in 2021, the Wisconsin State Crime Lab said they were a match. Investigators then went back to the Olkwitz case and found Tappendorf's name.

Court documents said Tappendorf, a truck driver, made deliveries to Kenworth in the days before Oklwitz was killed. He died in 2008 and was buried at Holy Cross.

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This spring, Tappendorf's son provided a DNA swab to investigators, which found the profile in the homicide was "very likely" from Clarence Tappendorf.

That's what led investigators to Holy Cross on a summer day to try to close two cold cases – and see if there are ties to any others.