Do you know who murdered 20 year old Diane K. Olkwitz in 1966? On the afternoon of November 3, 1966, a grim discovery was made in the quiet Village of Menomonee Falls, Wisconsin. Nineteen-year-old Diane J. Olkwitz, a female secretary, was found deceased in the shop area of her workplace, Kenworth Manufacturing Company. The scene was one of horrific violence; she had been brutally stabbed more than 100 times. The Menomonee Falls Police Department launched an immediate and intensive investigation into the shocking crime that had taken the life of the young
woman.
For decades, the case of Diane Olkwitz's murder remained a painful open wound for her family and the community. Investigators pursued numerous leads and looked into various persons of interest over the years. Evidence, including crucial DNA samples, was meticulously collected from the scene in 1966, a forward-thinking step that would prove vital many years later. Despite their efforts, which included interviewing potential suspects and comparing samples, the investigation went cold. Theories and rumors circulated, but no arrests were ever made, leaving a lingering sense of uncertainty and a lack of closure for Diane's loved ones. The passage of time did little to erase the memory of the brutal crime, and the case was never forgotten by law enforcement.
The relentless march of science and technology would ultimately provide the key to unlock the decades-old mystery. In October 2021, investigators revisited the cold case, armed with the new potential of forensic investigative genetic genealogy. This advanced DNA testing led to a breakthrough in February 2023. The DNA profile from the 1966 crime scene was not only identified but was also linked to a second unsolved homicide from 1971, that of Terri Erdmann in Milwaukee. The investigation identified a suspect, Clarence Marcus Tappendorf.
Tappendorf, a delivery driver, had been questioned in the initial 1966 investigation. Records showed that on the day of Diane's murder, he had made a delivery to a business located directly across the street from Kenworth Manufacturing. However, he was never charged. Investigators located living relatives of Tappendorf, who had passed away in 2008, and obtained DNA samples which confirmed a familial link. To be absolutely certain, authorities exhumed Tappendorf's remains for a direct DNA comparison. The test results were definitive, confirming that Clarence Marcus Tappendorf was the man responsible for the murders of both Diane Olkwitz and Terri Erdmann. After more than half a century of questions, the identity of the killer was finally brought to light, closing a case that had haunted two communities for generations.
