I'm Lester Holt. Tonight on Dateline, she was a woman determined to change the world, but when she disappeared one summer's night, her family's world was changed forever.

The feeling that you're leaving your child

for the last time.

It was horrible.

We find her shoes. The screams missing from the window.

She fought back and she scratched that individual.

There was plenty of DNA.

There was a DNA under every finger, no.

You learn about the argument with the boyfriend.

This is a guy trying to build an alibi.

That's what it sounds like.

Things didn't add up.

You didn't think this was someone close to her.

No. I wanted answers.

Someone that could do this could hurt other people.

But you were to see.

Somebody else.

I'm just going to go. I just knew he was in the house.

I just knew he was in the house. Here's Josh Mankowitz with the woman who couldn't scream.

Here's Josh Mankowitz with the woman who couldn't scream. Now, one, one city.

In November 2003, two women were barricaded inside their bathroom in Las Cruces, New Mexico and desperately calling 911.

What's your emergency?

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