For more than three decades, the murder of 21-year-old college student Tammy Zywicki has remained one of the most haunting unsolved cases connected to America’s highways. She disappeared after her car was found abandoned along Interstate 80 in Illinois in August 1992. Nine days later, her body was discovered nearly 500 miles away in rural Missouri.
Now, 34 years after Tammy’s death, Illinois State Police and the FBI have announced a significant new lead. Investigators have identified Theresa “Teri” Belenske as a person of interest who may have had a connection to an unknown truck driver seen near Tammy’s vehicle around the time she disappeared.
Police have emphasized that Belenske is not a suspect in Tammy’s murder. Instead, investigators are asking the public to provide information about her life, her travels, and especially the people she may have traveled with during the late 1980s and early 1990s.
The announcement has brought renewed attention to a case that has remained unsolved since 1992.
A College Student’s Journey Turns Into a Nightmare
Tammy Zywicki was a 21-year-old student at Grinnell College in Iowa. Described by those who knew her as energetic, independent, and determined, she was preparing to begin her senior year of college.
On August 23, 1992, Tammy left Evanston, Illinois, and began driving west toward Grinnell, where she was expected to arrive later that evening.
But Tammy never made it.
Between approximately 3:10 p.m. and 4:00 p.m., she was reportedly seen near her vehicle at mile marker 83 on Interstate 80 in LaSalle County, Illinois. Her car, a white 1985 Pontiac T1000, had apparently experienced trouble.
At some point after Tammy was last seen, she disappeared.
An Illinois State Police trooper found her vehicle along the interstate and marked it as abandoned. The car was later towed on August 24. That same evening, Tammy’s mother contacted Illinois State Police after realizing her daughter had never arrived at college.
What should have been a routine drive back to school had become the beginning of a nationwide search.
A Body Found Hundreds of Miles Away
For more than a week, there was no sign of Tammy.
Then, on September 1, 1992, the terrible truth emerged.
Tammy’s body was discovered along Interstate 44 in rural Lawrence County, Missouri, between Joplin and Springfield. She had been stabbed to death.
The distance between where Tammy was last seen in Illinois and where her body was discovered in Missouri added another disturbing layer to the investigation. Whoever was responsible had apparently transported her body hundreds of miles across state lines.
Authorities also learned that a semi-truck had reportedly been seen near Tammy’s vehicle around the time she disappeared.
The driver was described as a white man between 35 and 40 years old, standing more than six feet tall and having dark, bushy hair.
For decades, that description has remained one of the most important clues in the investigation. Yet despite countless hours of work, investigators were unable to identify the person responsible for Tammy’s death.
A Case That Refused to Be Forgotten
Over the years, Tammy’s case became a cold case, but it was never officially abandoned.
Illinois State Police and the FBI continued to examine evidence, follow leads, and revisit old theories. Investigators have reported that approximately 200 pieces of evidence remain connected to the case.
As forensic science has advanced, authorities have also been able to revisit evidence that could not be fully analyzed using the technology available in 1992.
DNA testing has become a major focus of the investigation. According to the FBI, investigators have reviewed physical evidence with the hope that modern forensic techniques could uncover DNA that was impossible to detect decades earlier.
Some of Tammy’s personal belongings were also never recovered.
Among the missing items are a Canon 35mm camera, a Lorus musical wristwatch that played “Raindrops Keep Falling On My Head,” and a distinctive red-and-white soccer patch connected to the St. Giles Soccer Club in Greenville, South Carolina.
Investigators hope that someone may remember seeing these items or know where they ended up.
Even a seemingly small detail could potentially lead investigators closer to the person responsible.
A New Person of Interest
On August 23, 2026—the 34th anniversary of Tammy’s death—Illinois State Police and the FBI announced a new development.
Investigators identified Theresa “Teri” Belenske, whose maiden name was Theresa Vega, as a person of interest in the investigation.
According to authorities, Belenske was known to hitchhike and may have traveled with the unknown truck driver investigators believe could be connected to Tammy’s disappearance and murder.
Police are particularly interested in learning about Belenske’s activities from the late 1980s through the mid-1990s.
Belenke had connections to several cities in California, including Oceanside, Vista, Pomona, San Bernardino, and Fontana, according to investigators.
She would have been approximately 32 years old at the time of Tammy’s death.
Belenke died in 2014 at the age of 54.
Authorities have made it clear that she is not considered a suspect in Tammy Zywicki’s murder. Instead, they believe she may have information—or may have known someone—who could help identify the person responsible.
The key question investigators now want answered is simple but potentially crucial: Who was Theresa Belenske traveling with during that period of her life?
Why Investigators Need the Public’s Help
After 34 years, memories can fade and witnesses can disappear. But cold-case investigators know that people sometimes remember important details years later.
Someone who knew Belenske may remember a truck driver she spent time with. A former friend, relative, coworker, or fellow traveler may have seen something that did not seem important at the time.
That information could now become a critical piece of the puzzle.
Illinois State Police have released photographs of Belenske, including an older photograph and an AI-generated image intended to show what she may have looked like in 1992.
The goal is to reach people who may have known her decades ago and encourage them to come forward.
Investigators are also continuing to pursue DNA evidence and other forensic leads.
The FBI is offering a reward of up to $50,000 for information leading to the identification of the person or people responsible for Tammy’s murder.
Thirty-Four Years Without Answers
Tammy Zywicki was only 21 years old when her life was taken.
Her family has spent decades without knowing who was responsible. Her friends have grown older, her classmates have moved on with their lives, and generations of investigators have worked on the case.
Yet Tammy’s name has never disappeared from the public conversation.
The new person of interest does not mean the case has been solved. Police still have not named a suspect or announced an arrest.
But after decades of uncertainty, investigators believe this new lead is worth pursuing.
Someone, somewhere, may have information about Theresa “Teri” Belenske and the people she traveled with during the years before Tammy’s death.
That person may not realize that a memory from more than 30 years ago could help solve a murder that has remained unanswered since 1992.
For Tammy’s family and investigators, the search continues.
After 34 years, there is still no confirmed answer to the question that has haunted this case since the day a young college student vanished from Interstate 80:
Who killed Tammy Zywicki?
Anyone with information about Tammy Zywicki’s murder, Theresa Belenske, or the people she may have traveled with during the late 1980s and early 1990s is encouraged to contact Illinois State Police or the FBI. Authorities say tips can remain anonymous.
