I'm Lester Holt, tonight on Dateline, Drew Peterson, convicted of murdering one wife and a suspect in the disappearance of another.

After 14 years, there are still so many secrets, and now Drew Peterson is talking again.

My sister was my love.

My best friend, Stacey told me if anything happens to me, Drew did it.

Once Stacey went missing, of course, people start saying, wait a minute, his other wife died in the bathtub.

He said, Neil, I've done a lot about things in my life.

Who always did my dad? Either he has the worst luck in the world or he's responsible for murdering two women.

I wanted them to know the truth.

I was talking to this lady. She's pretty or no?

It was almost as if he considered himself like a celebrity.

It didn't do it. You didn't do what? Kill Kathleen or make Stacey disappear.

So everybody's making things up.

A lot of people are.

You may be here for the rest of your life.

Maybe, but I may not be.

What keeps me going is my love, my heart.

And I will find her and I'll bring her home. And that's my promise.

Here's Natalie Morales with Influence.

I just think about, like, is this ever going to end? Am I ever going to be able to find her and, you know, keep the closure I need?

In these murky, churning waters, a sister searches for answers.

Can I keep doing this every day I can and every day I can afford until the day I die? Until I can bring her home.

Solving that mystery would close the circle on a notorious and sensational case, the disappearance of Stacey Peterson.

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