For years, JoAnn Zywicki has wondered who killed her daughter, Tammy Zywicki, back in 1992 on her drive back to college before the start of her senior year.
Athletic, upbeat and a talented amateur photographer, Tammy, 21, vanished on Aug. 23, 1992, after her car broke down on I-80 in Illinois, near LaSalle. Prior to her disappearance, she had dropped her brother off at Northwestern University in Evanston and was heading to Grinnell College in Iowa.
On Sept. 1, her body was found 500 miles south, wrapped in a blanket, on the side of a Missouri interstate.
“Many times it’s come into my mind who this person is [who killed her],” JoAnn, 78, tells PEOPLE. “What kind of life have they been living? Are they still alive? Do they have a family?”
Now police say they may be closer than ever to catching Tammy’s killer — and bringing her family justice.
“We have continued to work and will continue to work until it gets solved,” says Lt. Jeff Padilla of the Illinois State Police in the premiere of the fifth season ofPeople Magazine Investigateson Monday, March 22 at 10 ET/9 CT on Investigation Discovery on Investigation Discovery and discovery+. “I am optimistic that this case is going to be solved within the next year.”
(An exclusive clip of Monday’s episode is shown above.)
Tammy Zywicki.Courtesy Zywicki Family

TitledHighway Horrors, Monday’s season-opening episode centers on Tammy’s promising life, her troubling disappearance and her horrific murder — and how police and her family have been searching for her killer ever since.
Upon learning of Tammy’s disappearance, her older brother, Todd Zywicki, then a student at the University of Virginia Law School, dropped everything and rushed to Illinois to help find her.
A truck that was seen near where Tammy Zywicki’s car broke down in 1992.FBI

“We did everything we could in terms of generating media attention and spreading the word,” says Todd, 55, a law professor at George Mason University in Virginia.
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Sadly, nine days later, Tammy’s body was found. She’d been stabbed eight times.
A circular “St. Giles Soccer Club” patch was missing from the shorts she was wearing. So was the whimsical Lorus watch with a forest green watchband and a white face with a green umbrella in the middle that played “Raindrops Keep Falling on My Head” and her trusty Canon 35 mm camera.
Patch missing from Tammy Zywicki’s shorts.FBI

Investigators believe the killer may have taken the items, possibly as souvenirs.
A watch similar to the one Tammy Zywicki was wearing when she vanished.FBI

“I would like people to continue to look for the watch and the patch from Tammy’s shorts,” Padilla says in the episode.
“If we could locate that patch or if somebody knew where that patch was, that would point us in the direction of a suspect,” he adds.
The Zywicki family.Courtesy Zywicki Family

JoAnn is holding out hope that investigators will one day find her daughter’s killer.
“I get asked the question, ‘Why do you really care who did it?'” she says. “‘It’s over, done with.’ “But I think about Tammy every day when I get up and see her picture,” she says.
“She had a lot of good things ahead of her.”
For more on this story, watchHighway of HorrorsonPeople Magazine Investigates, premiering Monday, March 22 at 10 ET/9 CT on Investigation Discovery and streaming on discovery+.
source: people.com