Diane Olkwitz and Terri Lee Erdmann. Credit: Milwaukee Police Department
On Nov. 3, 1966, Diane Olkwitz was found deceased in the shop area of Kenworth Manufacturing Company in the Village of Menomonee Falls (WI). Diane was 19 years old at the time and she had been brutally stabbed multiple times.
The Menomonee Falls Police Department responded and initiated an investigation that included obtaining evidence from the victim that would later provide a crucial role in solving this crime through the advancements of DNA science.
Over the years numerous persons of interest and potential suspects were identified, researched and interviewed. Detectives assigned to this investigation pursued those leads and oftentimes obtained DNA samples, hair samples, and/or fingerprint cards from those persons to be sent for analysis. Eventually, due to the quality of the DNA samples preserved from the crime scene in conjunction with the advances of forensic science, additional investigative opportunities presented themselves.
Armed with this new investigative potential, in October 2021, Detective Chris Bellows (Menomonee Falls Police) met with the staff of the State of Wisconsin Crime Laboratory about the use of forensic investigative genetic genealogy. This follow-up effort expanded to involve the Milwaukee Police Department Cold Case Unit, who were reviewing similar unsolved cases from their agency. In addition, the Federal Bureau of Investigation became involved, along with additional state and federal analysts to review the available evidence.
Through these efforts it was determined that a similar suspect DNA profile existed for a 1971 unsolved homicide case in the city of Milwaukee. Then, in February 2023, through investigative efforts that utilized forensic investigative genetic genealogy, a potential suspect was identified. Regrettably, the investigation revealed the suspect had passed away in 2008. However, living descendants of the suspect were located, interviewed and provided DNA samples.
The Menomonee Falls Police Department is accredited by the Wisconsin Law Enforcement Accreditation Group Based on an analysis of those samples, a warrant was obtained to exhume the suspect’s remains for further DNA analysis and comparison.
Through these collective efforts of all involved agencies combined with the DNA testing completed by the State of Wisconsin Crime Laboratory, the suspect responsible for the murder of Olkwitz (Menomonee Falls) and Terri Erdmann (Milwaukee) was determined to be Clarence Marcus Tappendorf.
A review of the Olkwitz case file revealed that during the week following the homicide in November 1966, investigators sent questionnaire forms to all of the companies identified as having made deliveries/pick-ups to Kenworth Manufacturing. Clairmont Transfer of Milwaukee replied to the request with a completed questionnaire. The questionnaire indicated the company did not have any deliveries or pickups to Kenworth Manufacturing on Nov. 3, 1966; however, its most recent delivery was made on Oct. 31, 1966, by delivery driver Clarence Tappendorf.
Additionally, the company indicated that on Nov. 3, 1966, Tappendorf made a delivery in the area of Kenworth Manufacturing to a business called Inland GM Diesel. This was located across the street from Kenworth Manufacturing.
The Menomonee Falls Police Department would like to thank the following investigative partners who played key roles in keeping this investigation moving forward and allowed our department to identify the suspect responsible for this heinous murder: the Milwaukee Police Department, the Wisconsin Department of Justice, the Federal Bureau of Investigation along with our very own dedicated department members, some of whom have since retired. Finally, and most importantly, we would like to thank the Olkwitz family for their assistance, patience and perseverance. Our thoughts are with the Olkwitz family and we hope the conclusion of this case provides some measure of closure.
Republished courtesy of Village of Menomonee Falls Police Department