ST. LOUIS (AP) -- Two decades since her daughter was stabbed to death along an Illinois highway while headed back to college, JoAnn Zywicki has weathered the onslaught of birthdays, holidays and special occasions that often torment families of the murdered.
The fact that no one ever was arrested compounds the struggle of the 70-year-old mother of the murdered young woman, Tammy Zywicki. Over the years, she has watched as the police followed new leads and focused on new suspects, including an ex-con trucker who then died of AIDS, but mostly she has learned how to cope.
"You just go into a pattern of maybe acceptance that that's the way it is," JoAnn Zywicki said from her home in the central Florida town of Ocala. "I feel fortunate we were able to get through this, and I can see why some people can't handle it. You have to be tough and not let it take over your life. She'd be the first person to say, `Go on.'
Twenty years ago this August, Tammy Zywicki's body was found wrapped in a blanket sealed in duct tape in southwestern Missouri, hundreds of miles from where she'd been last seen alive near her broken-down car along a central Illinois freeway.
Tammy had just dropped off her younger brother at Northwestern University in suburban Chicago and turned her 1985 Pontiac T1000 toward Iowa's tiny Grinnell College, where she played soccer and would have been a senior. Then 21 and from Marlton, N.J., Tammy was mulling graduate school, aspiring to perhaps teach Spanish some day.
It wasn't meant to be.
After her car broke down along Interstate 80 near LaSalle, Ill., a passer-by caught the last glimpses of Tammy alive there on August 23, 1992, at mile marker 83. Some witnesses said a tractor-trailer was seen parked behind her car. Others say they saw a pickup truck.
Tammy's body turned up nine days later just east of Joplin, Mo. The 5-foot-2, 120-pound woman, who once wrote in a high school journal she didn't want to suffer when she died, had been stabbed repeatedly in the chest and bled to death.
The horror of the story grabbed headlines: A young woman, described by her mom as an all-American "girly girl," is snatched up, possibly by a predator trucker prowling the nation's highways posing as a Good Samaritan.
After Tammy's body was found, Illinois State Police joined forces with the FBI and other agencies in a task force, but it disbanded the next year. While calling the investigation still active, FBI spokeswoman Joan Hyde in Chicago declines to be more specific.
"We remain optimistic that we'll be able to locate and charge the people responsible for this," she said.
Over the past two decades, efforts to crack the case have sputtered. Investigators looked at truckers suspected in killings and sexual attacks elsewhere, from North Carolina to California, but eventually eliminated them from suspicion in Tammy's death.
At one point authorities focused on Bruce Mendenhall, a southern Illinois trucker arrested in 2007 and suspected of fatally shooting women in Tennessee, Indiana and Alabama after their heads were wrapped in plastic wrap and duct tape. Authorities believe Mendenhall, serving a life sentence for killing a young woman at a Nashville truck stop, preyed on prostitutes. He had been a trucker for 20 years.
After his arrest, Nashville police fielded dozens of inquiries from law enforcement officials and families across the country hoping Mendenhall would be able to provide clues to unsolved murders going back as far as two decades. Nashville Detective Sgt. Pat Postiglione said the trucker hasn't been ruled out as a suspect in the Zywicki case.
"Any time you have a (suspect) like Mendenhall, you never want to exclude them entirely," Postiglione said. "He could have easily been where (Tammy Zywicki) was, and there'd be no paper trail linking him to that area."
Then there's Lonnie Bierbrodt, the late, ex-con trucker that JoAnn Zywicki and former Illinois State Police investigator Marty McCarthy consider the case's most-promising lead.
Bierbrodt had done prison time for armed robberies and was paroled before taking a job with a small trucking firm. Originally from the Illinois area where Zywicki was last seen alive -- he was visiting his brother at the time she disappeared -- Bierbrodt's Missouri trailer home wasn't far from where her body was found.
A witness told McCarthy she saw a man matching Bierbrodt's description with Tammy Zywicki and her broken-down car as she passed by on the interstate. The Datsun pickup truck the witness said she saw behind Zywicki's vehicle matched one Bierbrodt had before he steam-cleaned and sold it just days after the killing, McCarthy said.
Not long after the killing, Bierbrodt gave his then-wife a musical watch similar to one Tammy was said to have taken with her on the trip back to college. Tammy's body was found wrapped in a blanket with a Kenworth logo, and Bierbrodt drove a Kenworth-made truck.
Yet McCarthy says prosecutors resisted charging Bierbrodt, figuring there wasn't enough evidence to take the case before a grand jury. Bierbrodt was 41 when he died of AIDS in 2002.
"In 20 years, let's face it, no other suspect has come forward other than Bierbrot. He's a helluva suspect," said McCarthy, 65 and now retired in Wheaton, Ill., outside Chicago. "I'm an old cop, and these kinds of things just bug the hell out of me. But I'll keep fighting."
So will JoAnn Zywicki.
Never a believer in shrines, the mother long ago packed up her daughter's bedroom and gave most of the stuff to charity, saving only soccer plaques, yearbooks and photographs to keep a bit of Tammy close. Subtle reminders of the beach-loving girl grace her parents' home, from her Garfield bubble gum machine and seashells on a bathroom counter to more seashells tucked in a grandfather clock -- the first thing the parents see each morning. Her jewelry box is on her mom's dresser.
Zywicki watches her seven grandchildren romp around and regrets that her daughter never had the chance to add to that growing family.
"You kind of mourn what you lost, appreciate what you still have and just try to get through it whatever way you can," she said. "If it means sleeping in until noon because you're feeling down, that's what you do. Then you get up the next day and start it all over again."