A Knock On The Door

Detectives Revisit 1982 Murder Mystery

(CBS) 
"I believe she did this because she couldn't get a divorce," says District Attorney Morrison. "In her mind, it was much better to be the widow Harmon than the divorcee Harmon."

Morrison believed Melinda was unhappy in her marriage and caught up in a secret affair with Mangelsdorf.

But because of their strong religious beliefs, Morrison doubts it was sexual. "The promise of sex, the lure of sex unfulfilled, it can be stronger than the actual thing," he says.

The conservative Christian world they lived in had strict rules of behavior.

"You didn't go to the movies, we didn’t dance," explains Mark Wood, who was a student at MidAmerica Nazarene University at the time. "The old joke we used to have back then was 'you don’t smoke and you don’t chew and you don’t date girls who do.'"

And when you married, you married for life.

"Back in 1982 in the Nazarene church, divorce was not the option that it is today," says Morrison. "It would have not been a good thing. It would have caused a certain amount of shame and scandal."

But Don Stelting says to believe that, one would have to not know the Nazarene church at that time. "To think that someone would plan murder to avoid divorce, is ludicrous," he says.

Mark and Melinda always denied they had a romantic relationship and at first cooperated with investigators. But that soon stopped and leads dried up.

Investigators had a bloody murder scene but no footprints or fingerprints and no murder weapon. There was not enough evidence to prosecute.

"The question of 'Is that going to be provable beyond a reasonable doubt?' probably wasn't quite there," says Morrison.

With no charges holding them back, Mangelsdorf and Harmon both left Olathe.

Melinda headed back home to Ohio with her parents, while Mark went off to Harvard Business School and became a successful corporate executive.

He and his second wife, Christina, live in a million-dollar home in Pelham, N.Y., just outside New York City. He's the father of four, with one more on the way.

The Mangelsdorfs sat down with 48 Hours for their only television interview.

"Definitely, I went on with my life and it's not something that you know I really dwelled on or focused on a lot," says Mangelsdorf.

Kristina says she first learned about the case shortly after she started dating Mark. "My first reaction was this is the most ridiculous thing I've ever heard of; there's no way that he could have done this. You know he didn't need to give me any of the facts of the case or any assurances that he hadn't, to know that. You know, no, I mean it's not in his personality."

"The fact that the police considered me a suspect in the course of their investigation was hurtful and you know certainly leaves an impression on you," says Mark.

Asked if he killed David Harmon, Mark replied, "I did not kill David Harmon."

Mark doesn't believe Melinda was involved, either. "I mean, Melinda was my good friend and I choose to believe that - that that was not in her character," he says.