The murder of Tammy Zywicki
Lasalle County, Illinois · August 23, 1992
On the 34th anniversary of her disappearance, Illinois State Police and the FBI named a deceased woman who hitchhiked as a person of interest in the roadside abduction of a college student, and said items were being retested with modern DNA technology.
Overview
On Sunday, August 23, 1992, 21-year-old Grinnell College senior Tammy Zywicki dropped her brother off at Northwestern University in Evanston, Illinois, and set out for Iowa in her white 1985 Pontiac T1000. Illinois State Police say she was last seen with the car on Interstate 80 at mile marker 83 in LaSalle County between 3:10 and 4:00 p.m., and that a semi-truck was reported near it. A trooper ticketed the car as abandoned that day, and her mother told state police the next evening that she had not arrived at college. On September 1, her body was found along Interstate 44 in rural Lawrence County, Missouri; she had been stabbed to death. A multi-agency task force was disbanded the following year, and no one has been charged. On August 23, 2026, the 34th anniversary, state police and the FBI announced a new lead: a woman who died in 2014, known to hitchhike, who may have traveled with the unidentified truck driver. Police call her a person of interest, not a suspect, and say evidence is being retested with modern DNA technology.
Where it stands
The case is open and no one has been charged. The most recent development came on August 23, 2026, the 34th anniversary of Zywicki's disappearance. Illinois State Police and the FBI announced a new lead and named Theresa "Teri" Belenske, who died in 2014 at age 54, as a person of interest. The release said she was known to hitchhike and may have been traveling with the unknown truck driver before Zywicki's death, and it stated plainly that she is not a suspect. Investigators asked for information about her from the late 1980s through the mid-1990s, and noted ties to several California cities. The release also said that ISP and the FBI are examining 200 pieces of evidence and retesting items with modern DNA technology. FOX 32 Chicago reported that, according to state police, Belenske's DNA was found on the blanket in which Zywicki's body was wrapped; the written release does not say so, and it is the television station that attributes the claim to state police. The FBI reward of up to $50,000 remains. The case has seemed close before. A former trucker whom a retired state police investigator publicly named as the likeliest suspect died in 2002, and a state police master sergeant said in 2015 he did not believe the man had her watch. In 2020, a trucker arrested in Iowa in other killings briefly drew attention until state police said he did not appear to have been involved. Accounts also differ on the vehicle near her car: most describe a tractor-trailer, while one 2017 account says other witnesses reported a pickup truck. The truck driver remains unidentified.
Persons of interest
The theories below are reported strictly as attributed to the cited sources. Naming a person here is not an accusation. Individuals are named only where they are deceased, were formally charged, were officially named by authorities, or have been publicly cleared.
- Theresa "Teri" BelenskeDeceased
Illinois State Police and the FBI said in August 2026 that Belenske, who died in 2014 at age 54, was known to hitchhike and may have traveled with the unknown truck driver before Zywicki's death. Police said she is a person of interest, not a suspect. FOX 32 Chicago reported, attributing it to state police, that her DNA was found on the blanket in which Zywicki's body was wrapped.[1]
- The unidentified truck driverNot publicly named
The FBI and state police describe the driver of a semi-truck seen near Zywicki's car as a white man between 35 and 40, over six feet tall, with dark, bushy hair. He has never been publicly identified.[5]
- Lonnie BierbrodtDeceased
NBC Chicago reported that a retired state police investigator publicly named Bierbrodt, a former trucker, as the most likely suspect. He was questioned by investigators and died in 2002. A state police master sergeant said in 2015 that he did not believe Bierbrodt had Zywicki's watch.[9]
- Clark Perry BaldwinCleared
A retired state police investigator said after Baldwin's 2020 arrest in Iowa, on charges in other killings, that those allegations fit the profile of Zywicki's killer. Illinois State Police said days later that, at this time, he does not appear to have been involved in her murder.[10]
Sources
- Illinois State Police Seeks Public Assistance on Anniversary of Tammy Zywicki Murder
“Belenske is not a suspect, but a person of interest.”
- 1992 kidnapping and murder case remains active as authorities seek person of interest
“A semi-truck was seen near Zywicki’s car around the time she disappeared, according to state police.”
- Ozarks Unsolved: A big break in the case of Tammy Zywicki
“State Police said the case remains active with ISP and the FBI “exploring new leads, examining 200 pieces of evidence, and retesting items with modern DNA technology.””
- Tammy Zywicki cold case: New DNA lead emerges in investigation
“In fact, Theresa Belenske’s DNA was found on the blanket Tammy’s body was wrapped in, according to state police.”
- Tammy J. Zywicki
“After 25 years, the murder of 21-year-old Tammy Zywicki remains unsolved, but the FBI and the Illinois State Police believe new techniques for testing DNA may help reveal the killer’s identity.”
- 20 years later, hunt continues for Zywicki’s killer
“Investigators had a suspect early on who was never charged.”
- The FBI will pay if you can crack this 25-year-old murder mystery
“Illinois State Police and the FBI worked with other agencies after Zywicki’s body was found, but the task force was disbanded the following year.”
- Forensic Group Asked to Look For New Clues in Murder of Student
“On Tuesday, the Illinois State Police said it was turning it over to a private forensic group, in the hope of finding new clues.”
- Police Pursue Promising New Leads in Zywicki Investigation
“But Padilla said based on investigative information he has seen, he did not believe Bierbrodt was in possession of Tammy’s watch.”
- Tammy Zywicki Case: Illinois Police Say Iowa Man Not Involved in 1992 Slaying
“The Illinois State Police said Friday that Clark Perry Baldwin is not a suspect in the death of 21-year-old Tammy Zywicki.”
- Suspect eliminated, police still looking for answers in ’92 disappearance
“the ISP indicated that "at this time, Baldwin does not appear to have been involved with the murder of Tammy Zywicki."”