Richard Schlesinger (48 Hours Correspondent)

And the boss has said, no way.

We're not going to open a case of this magnitude with your gut feeling and embarrass the department and embarrass Mr. Winger.

As the years passed, Mark's new wife adopted his child and they had two other children.

And then, all of a sudden, the whole case got turned on its head.

We got a lucky break.

What was that?

Deanne Schultz.

Deanne Schultz was Donna's best friend.

Here's Aunt Deanne.

And she was deeply troubled.

For three and a half years, Deanne had kept a secret, and what she was finally ready to say would change everything.

It was a shock to everyone, especially Cox, who right after Donna's murder had written, it was very apparent that he and his wife were very much in love and that this should have never happened.

And now Deanne Schultz, just like that, says we were having an affair?

Yes.

What did you make of that, detective?

I said we got the evidence we need.

Deanne told them the affair began a month before Donna's murder and continued a few months after she died.

till Winger ended it.

And she dropped an even bigger bombshell.

She told police Mark wanted out of his marriage so badly he had talked about killing Donna.