MENOMONEE FALLS – After a combined 109 years of unsolved questions and no arrests, a killer has been confirmed in the stabbing deaths of two Southeast Wisconsin women.
At a press event at the Menomonee Falls Village Hall, authorities officially identified Clarence Marcus Tappendorf as the murderer of both Diane Olkwitz in 1966 and Terri Lee Erdmann in 1971.
On Thursday, November 3, 1966 at 5:10 p.m., Diane J. Olkwitz was found deceased in the shop area of Kenworth Manufacturing Company located at N56 W13777 Silver Spring Dr. in the Village of Menomonee Falls. Diane was 19 years old at the time and she had been brutally stabbed over one hundred 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. 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 of 2021, Menomonee Falls Detective Chris Bellows met with the staff of the State of Wisconsin Crime Laboratory about the use of forensic investigative genetic genealogy, which had been developed in 2019. 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 of Erdmann.
Then, in February of 2023, through investigative efforts that utilized forensic investigative genetic genealogy, a potential suspect was identified. An investigation revealed the suspect had passed away in 2008. However, living descendants of the suspect were located, interviewed and provided DNA samples.
“”Our investigative teams would identify potential relatives of our suspect, and we would go out and make contact with them, we would ask for their cooperation, and we would ask if they would be willing to share their DNA information with us to further our investigation” explained Bellows on Tuesday.
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, Tappendorf was determined to be responsible for the murders of Olkwitz and Erdmann.
Wisconsin Attorney General Josh Kaul said a combination of technological advancements, collaboration between local, state, and federal authorities, and cooperation from local citizens, all led to answers in the case.
At the presser, Menomonee Falls Chief Mark Waters and Milwaukee Chief Jeffery Norman both offered their condolences to the family. “I know this is not going to bring back your loved ones, but hopefully this will provide some level of closure and healing in regards to this particular horrendous incident” Norman said.
Norman Gross, a former classmate of Olkwitz’s, echoed that sentiment, saying he never gave up hope that her killer would eventually be revealed. “Just going to class reunions and stuff, her name was always there…she’s always on your mind. All these years and…finally it’s come to a conclusion.”
