Killing of college student Tammy Zywicki, who disappeared in Illinois, back in the TV spotlight

A few persons of interest have been identified over the years, but advances in DNA technology slowly ruled those individuals out. Though the case has gone unsolved for nearly 30 years, retired Illinois State Police lieutenant Jeffrey Padilla expressed confidence in the investigation. “I am optimistic that this case is going to be solved within the next year,” he says on the Season 5 premiere of “People Magazine Investigates.”