Wisconsin DOJ & FBI Leverage Othram’s Genetic Testing Platform to Solve the Murders of Diane Olkwitz and Terri Erdmann

Clarence Marcus Tappendorf has been identified as the suspect in the murders of 19-year-old Diane Olkwitz and 14-year-old Terri Erdmann, both murdered more than a half-century ago.

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Published November 16, 2023 by Michael Vogen
Media Inquiries


In 1966, 19-year-old Diane Olkwitz was murdered at her workplace in Menomonee Falls, Wisconsin, which is located in the Greater Milwaukee area. Five years later, in 1971, the body of 14-year-old Terri Erdmann was discovered in a field on the northwest side of Milwaukee. Both women had been brutally stabbed numerous times. The murders were not immediately linked, and a suspect was not identified for either case.

For more than five decades, multiple law enforcement agencies were involved in investigating the murders of these two women. In 2021, the Milwaukee Police Department, the Wisconsin Department of Justice, and the FBI worked together to link the cases using DNA obtained at the crime scenes, confirming that the same man was responsible for the murders of Olkwitz and Erdmann. This was accomplished through standard forensic STR testing. Although the cases were linked, the suspect remained unidentified because he was not in CODIS.

In 2022, the Wisconsin Department of Justice, working with the Menomonee Falls Police Department, submitted forensic evidence to Othram in The Woodlands, Texas. Othram scientists used Forensic-Grade Genome Sequencing® to build a comprehensive DNA profile for the unidentified suspect. After successfully completing the process, the DNA profile was delivered to investigators who worked with the FBI's forensic genetic genealogy team to generate new leads in the case.

Empowered with these new leads, investigators were able to meet with genetic relatives of the unknown man. In October 2023, law enforcement announced the identity of the person responsible for the homicides of Diane Olkwitz and Terri Erdmann as Clarence Marcus Tappendorf. Tappendorf’s remains were exhumed to definitively link him to the crimes using DNA evidence. Unfortunately, Tappendorf cannot be charged in the murders of Olkwitz and Erdmann, as he died in 2008 at the age of 80 years.

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Michael Vogen

Michael Vogen

Director of Case Management

2829 Technology Forest Blvd Suite 100, The Woodlands, Texas 77381

Michael works with law enforcement agencies throughout the United States and Canada on “unsolvable“ cases that can benefit from advanced DNA testing methods. He helps these agencies use cutting edge DNA sequencing and new forensic techniques to develop investigative leads for their cases.

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About Othram Inc.

Othram is the world’s first private DNA laboratory built specifically to apply the power of modern parallel sequencing to forensic evidence. Othram’s scientists are experts at ... Read morerecovery, enrichment, and analysis of human DNA from trace quantities of degraded or contaminated materials. Founded in 2018, and located in The Woodlands, Texas, our team works with academic researchers, forensic scientists, medical examiners, and law enforcement agencies to achieve results when other approaches have failed. Follow Othram on Twitter @OthramTech or visit Othram.com to learn how we can help you with your case. With dnasolves.com anyone can make a difference and help solve the next cold case.