On August 23, 1992, Tammy J. Zywicki departed Evanston, Illinois, for college in Grinnell, Iowa, where she was expected to arrive that evening. Later that day, Zywicki's car was found by an Illinois State Trooper and ticketed as being abandoned. On August 24, 1992, the vehicle was towed by the Illinois State Police. On that same evening, Zywicki's mother contacted the Illinois State Police and advised them that her daughter had not arrived at college.
On September 1, 1992, Zywicki's body was located along Interstate Highway 44 (I-44) in rural Lawrence County, Missouri, which is located between Springfield and Joplin, Missouri. She had been stabbed to death.
Zywicki was reportedly last seen with her car (shown above) at mile marker 83 on I-80 in Central Illinois, between 3:10 p.m. and 4:00 p.m. on August 23, 1992. It was also reported that a tractor/trailer was seen near Zywicki's vehicle during this time period. The driver of the tractor/trailer is described as a white male between 35 and 40 years of age, over six feet tall, with dark, bushy hair. Some of the victim's personal property is known to be missing, including a Cannon 35mm camera and a musical wrist watch with an umbrella on the face.