Clarence Tappendorf

On October 25, 2023, police announced that Clarence Marcus Tappendorf is the lead suspect in the November 3, 1966 murder of 19-year-old Diane Olkwitz in Menomonee Falls, Wisconsin, as well as the June 24, 1971 murder of 15-year-old Terri Erdmann in Milwaukee, Wisconsin. The cases have been cleared by exception due to the death of Tappendorf in 2008.

Olkwitz was found stabbed to death at her workplace, a metal stamping plant, in Menomonee Falls. She had been stabbed over 100 times. Erdmann’s remains were found in a field after she did not return home the evening before. She had been stabbed about 60 times.

The cases were reopened and linked to a single suspect through DNA in December of 2021. A DNA profile was obtained in 2001 from Olkwitz’ clothing, which is described as a girdle undergarment. The DNA samples are described as being from a male, but there is no information as to whether they were developed from semen, or whether the women were sexually assaulted.

The FIGG investigation was led by the Menomonee Falls Police Department. There is no information on who performed the FIGG work. The initial confirmation was made through kinship testing with Tappendorf’s son in May of 2023. In June of 2023, police obtained a warrant to exhume Tappendorf’s remains from the Holy Cross Cemetery in Milwaukee. The final confirmation was made through a direct DNA comparison between Tappendorf’s DNA and that found at the crime scenes.

Police state that Tappendorf worked as a delivery driver, and that he had made a delivery to Olkwitz’s workplace, the Kenworth Manufacturing Co., four days before her murder. He was making a delivery across the street on the day of her murder.

Police state that Tappendorf did not have a criminal record, and that they continue to investigate whether he may be responsible for further offences.


Fogarty, Bridget, and D. Kwas. “Police Name Killer for Murders of 19-Year-Old Diane Olkwitz, 15-Year-Old Terri Lee Erdman.” Milwaukee Journal Sentinel, October 25, 2023. Accessed November 2, 2023.

Lemoine, Bret, and Fox6 News Digital Team. “Menomonee Falls Cold Cases Linked to Same Man, Dead for Years.” Fox6 News, October 25, 2023. Accessed November 2, 2023.

Village of Menomonee Falls Police Department. “DNA, Genealogy Point to Suspect in 1966, 1971 Unsolved Murders.” Forensic Magazine, October 27, 2023. Accessed November 2, 2023.


First Name Clarence
Last Name Tappendorf
Other Names
Victims 2 (Details)
IGG Started nd
Case Cleared 2023-10-25
IGG Org nd


Case ID Name Age Case Opened Location Investigating Org Most Serious Charge Disposition Court
2083 Diane Olkwitz 19 1966-11-03 Menomonee, WI Menomonee Falls PD Second degree murder Case was cleared by exception due to death of perpetrator n/a
2084 Terri Erdmann 15 1971-06-24 Milwaukee, WI Menomonee Falls PD Second degree murder Case was cleared by exception due to death of perpetrator n/a

Last updated: February 13, 2024

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Case data and narrative licensed under CC BY 4.0: Dowdeswell, Tracey (2023), “Forensic Genetic Genealogy Project v. 2022”, Mendeley Data, V1, doi: 10.17632/jcycgvhm96.1. All other content, including photos, have been added.