The Illinois State Police and the Federal Bureau of Investigation are urging the public to come forward with information regarding the cold case murder of Tammy J. Zywicki. The agencies announced a new lead on the anniversary of her disappearance, marking the 34th year since the incident occurred. Tammy Zywicki, a student from Evanston, Illinois, was last seen on August 23, 1992, between 3:10 and 4:00 p.m. near Interstate 80, mile marker 83, in LaSalle County, Illinois. She was traveling to Grinnell, Iowa, for college when her white 1985 Pontiac T1000 was found abandoned later that day. Her body was discovered the following day, August 24, 1992, along Interstate 44 in rural Lawrence County, Missouri, where she had been stabbed to death. Investigators are focusing on an unknown semi-truck driver described as a white male, aged 35 to 40, over six feet tall, with dark bushy hair, who was seen near the vehicle. Special agents are also investigating Theresa Belenske, a person of interest who may have hitchhiked with the suspect. Belenske, who passed away in 2014, had ties to several California cities including Oceanside, Vista, and San Bernardino. Authorities are seeking information about her movements and companions during the late 1980s and early 1990s. The FBI is offering a reward of up to $50,000 for information leading to the identification and arrest of those responsible. The investigation involves retesting 200 pieces of evidence with modern DNA technology. The public is encouraged to contact the Illinois State Police Investigative Tips page or call 1-800-CALL-FBI with any relevant information. Callers may remain anonymous. The case remains active as law enforcement continues to explore new leads and examine historical evidence to bring closure to the victim's family.