Tonight on Dateline, the first of our special Sunday mysteries.

Craig sent me a message and I knew something terrible must have happened.

He said, Hannah's jumped out the window.

What?

She did have a tendency to be a little bit off the rails when she was drunk.

I was very confused because I didn't see any signs.

She didn't say any goodbyes. There was no note.

She told me that she had had the affair with Craig's friend.

Craig was upset, you know, has to be expected.

There was deep gouches on both hands.

This is not a person that jumps out the window.

Did you think he had killed her?

Yes. Did he pick Hannah up and throw her out that window?

No. Hannah was really wonderful.

I just have to believe it was a terrible accident.

A deadly fall, followed by a father's suspicions.

You'll share his search for the truth.

I'm Lester Holt and this is Dateline.

Here's Dennis Murphy with The Window.

It's a funny thing looking back at photos of happy times.

You don't know yet which of them is doomed.

Her, him, maybe both.

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