A Knock On The Door

Detectives Revisit 1982 Murder Mystery

(CBS)  For the first time in 23 years, Mark and Melinda were together again - but this time the only thing they were sharing was the charge of murder.

Mark's testimony was crucial for Melinda's defense, and ultimately his own. The defense wanted to show Mark was not capable of murder and that he and Melinda couldn't have conspired to commit such a crime.

"I felt that it would be an opportunity for me to tell the truth, to potentially assist in uncovering the truth for the jury, giving them full information, full facts," Mark explains.

Mark's defense attorney, Mickey Sherman, said it was a gamble worth taking - even though anything Mark would say could be used against him.

Why was he so willing to have his client testify?

"The truth is the truth," says Sherman. "I felt that I'd rather put him on the witness stand now and let the jury, let the world know what his recollection was, rather than have this cloud over his head."

Questioned by Melinda's defense attorney Tom Bath, Mark answered questions point blank about accusations of an affair.

Asked if he was having an affair, romantically involved or physical in any kind of sexual way with Melinda, Mark said no.

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

Mark looked calm on the stand, even under tough cross examination from Morrison.

Mark told Morrison he was aware of the statements Melinda had made to police about an alleged relationship and that she thought he had killed David.

Defense attorney Sherman thought Mangelsdorf had done "fantastic" on the stand. For him, this was a dress rehearsal, where he got to see how his client would do as a witness.

But Hoffman believes Mark taking the stand may not have been the best defense for Melinda or for himself. "There were no feelings of sorrow for David. You know, it was all just rehearsed," says Hoffman. "I think it is a deep, defining moment of his personality. I think you really saw Mark Mangelsdorf as Mark Mangelsdorf - totally controlled, totally sure of himself. But something's wrong there."

Melinda never took the stand or spoke publicly about the murder of her husband.

After nearly three weeks of testimony and more than 60 witnesses, Melinda's trial came to a close. After two days, the jury reached a verdict.

Jurors found Melinda guilty of murder and conspiracy to commit murder.

Hoffman thinks Mark's testimony hurt Melinda. "It hurt her. If they believed him, they wouldn't (have) convicted her."

Out on bail, Mark was at home with his wife when they learned of Melinda's fate.

Mark says he was surprised and disappointed at the verdict. He says he thought she was innocent.

Kristina believed the outcome would be different for her husband. "It wasn't like we looked at this and said, you know, 'Oh my gosh, you know, the same thing is gonna happen to Mark.' I mean there's still a confidence that it's a very different case and that Mark will ultimately be found innocent," she says.

As Mark started to prepare for his own trial, Melinda, facing life in prison for the murder of her husband, sat in a Kansas county jail awaiting sentencing.