MADISON, Wis. -- Fond du Lac County investigators are reviewing a cold homicide case that started nearly two decades ago.

Berit Beck disappeared 19 years ago.

Her mother, Diane, said the Sturtevant teenager had just graduated from high school and was working a summer job that sent her to Appleton for computer training.

Police said Berit never made it to that training seminar on July 17, 1990. Six weeks later, a farmer found the young woman's body in a ditch in the Town of Waupun, according to authorities.

"The longer it goes on, the angrier you become because you don't have any answers yet," said Diane Beck in an interview with WFRV-TV.

"There's a kind of a saying that bad conscience has a good memory," said Dave Beck, the victim's father. "And I'm sure that they're (possible suspects) constantly reminded of this bad thing that happened, and that they need to fess up and say, 'I have some information that I've been holding for quite a while and I think I need to get it off my chest.'"

Berit Beck's family and investigators said they hope advances in DNA technology will lead to new clues, a suspect or even an accomplice, according to WFRV-TV.

Anyone with information is urged to call the Fond du Lac County Sheriff Department's Detective Division at 920-929-3370.