Illinois State Police Seeks Public Assistance on Anniversary of Tammy Zywicki Murder

NEW LEAD – identification of a person of interest

August 23, 2026

JOLIET – The Illinois State Police (ISP) and the Federal Bureau of Investigation (FBI) have a new lead regarding the kidnapping and murder of Tammy J. Zywicki. August 23, 2026 marks the 34^th anniversary of Tammy’s disappearance. Her case remains active as ISP and FBI continue exploring new leads, examining 200 pieces of evidence, and retesting items with modern DNA technology.

Tammy was reportedly last seen with her car on Interstate 80 at mile marker 83 in LaSalle County, IL between 3:10 and 4:00 p.m. on August 23, 1992. She left Evanston, IL for college in Grinnell, IA where she was expected to arrive that evening. Later that day, Tammy’s car, a 1985 White Pontiac T1000, was found by an ISP Trooper and marked as being abandoned. On August 24, 1992, ISP towed the vehicle. That same evening, Tammy’s mother contacted ISP and advised that her daughter had not arrived at college. On September 1, 1992, Tammy’s body was found along Interstate 44 in rural Lawrence County, MO, which is located between Joplin and Springfield, MO. She had been stabbed to death. It was also reported that a semi-truck was seen near Tammy’s vehicle during this time period. The truck driver was described as a white male between 35 and 40 years old, over six feet tall, with dark, bushy hair.

Special agents are looking for information about a person who may have a connection with the unknown truck driver. Theresa “Teri” Belenske (maiden name Theresa Vega) was known to hitch hike and may have been traveling with the unknown suspect at some point prior to Tammy’s death. Belenske would have been 32 years old at the time of Tammy’s death. She passed away in 2014 at the age of 54. Belenske is not a suspect, but a person of interest. Special agents are looking for information about Belenske from the late 1980’s through the mid 1990’s. Belenske has ties to cities in California, including Oceanside, Vista, Pomona, San Bernadino, and Fontana.

Anyone with information about Tammy’s killing, or Belenske and who she traveled with during the late 1980’s and early 1990’s, can leave a crime tip at our ISP Investigative Tips page or call 1-800-CALL-FBI. Callers can remain anonymous.

The FBI is offering a reward of up to $50,000 for information leading to the identification of the individual or individuals responsible for this crime.

Below are photos of Tammy and some of her personal property known to be missing, along with a photo of Belenske taken in 2009, as well as an AI generated image of what she may have looked like in 1992.

Missing items include a Cannon 35mm camera and a Lorus brand musical wristwatch, which played the tune “Raindrops Keep Falling On My Head.” Also taken was a red and white soccer patch monogrammed with “St. Giles Soccer Club, Greenville, SC.”

To hear more about the latest in the investigation, listen to the Illinois State Police Podcast, which can be found on many streaming platforms. https://lnk.bio/illinoisstatepolicepodcast.

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