Richard Schlesinger (48 Hours Correspondent)

There was no forced entry.

Somebody let him in.

And Harrington parked right in front of the Winger home, leaving behind a piece of paper with a puzzling message.

I saw that there was a note on the front seat, and it had Mark Winger's name, his address, and 4.30 p.m.

He says he doesn't know Roger Harrington, has never met him, and he does not indicate any appointment, when I have already seen the note which indicates an appointment.

There's always things in every homicide that don't fit.

So what did you do with those things that bothered you?

Just let them bother me, like they always do.

Cox saw no reason to doubt that the nuclear engineer justifiably shot a disturbed intruder.

But Williamson wanted to investigate further.

His bosses turned him down flat.

They discounted everything I said.

How did they discount it?

They just said the case is going to be closed, that's it.

And that's the way it stayed for three and a half years.

Until... You didn't know what she wanted to say.

No.

But you knew it was going to be big.

Yes.

A surprise witness came forward.