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.