Illinois Investigators Linked Person of Interest to Murder

Authorities identified a woman whose DNA was found at the 1992 crime scene of Tammy Zywicki.

Updated on Oct. 2, 2026 in Crime — General

Bold flat-color editorial illustration of a lone highway sign post under a distant streetlight, evoking a cold case investigation. — Illinois authorities have linked the late Theresa Belenske to the 1992 murder of Tammy Zywicki via DNA evidence found at the scene. AI Illustration. Upload story photo >

Illinois investigators have identified the late Theresa Belenske as a person of interest in the 1992 murder of Tammy Zywicki. Her DNA was discovered on a blanket at the crime scene, and authorities are now seeking information from the public in Southern California to help identify the primary suspect.

Why it matters

The identification of Belenske provides a potential breakthrough in a case that has remained unsolved for over three decades. Investigators believe she interacted with the perpetrator, who is suspected to be a male truck driver, and that her history could finally reveal his identity.

The 34-year-old investigation involved interviews with 37 eyewitnesses. DNA belonging to Theresa Belenske, who died in 2014 at age 54, was matched to a blanket found at the site.

The players

Tammy Zywicki

She was a college student whose 1992 disappearance and subsequent murder sparked a decades-long investigation.

Theresa Belenske

She was identified by Illinois investigators as a person of interest whose DNA was recovered from the crime scene.

The details

Investigators used artificial intelligence to create a composite image of what Belenske looked like in 1992, hoping to prompt memories from those who knew her in Southern California. While Belenske is deceased, officials maintain that her known connections to areas including Oceanside, Vista, Fontana, Pomona, and San Bernardino are critical to solving the case.

1980s: Theresa Belenske resided in Southern California.
August 23, 1992: Tammy Zywicki dropped her brother at Northwestern University.
August 31, 1992: The body of Tammy Zywicki was discovered in Missouri.
2014: Theresa Belenske passed away at the age of 54.
September 2026: Investigators officially announced the identification of Belenske.

Legal Context

This development follows a pattern of cold case resolutions driven by advanced DNA testing programs. The discovery marks a significant advancement in the investigation of the 1992 murder of Tammy Zywicki.

Residents in Southern California who may have known Belenske under her aliases, Theresa Vega or Theresa Belenske, are encouraged to contact investigators. This information is vital for law enforcement to track the movements of the primary suspect in this long-standing case.

The takeaway

The use of DNA testing and AI-generated imagery demonstrates how modern technology is breathing new life into cold cases from the 1990s. Even decades later, public assistance remains a critical factor in connecting the dots to identify perpetrators of violent crimes.