I'm Lester Holt, tonight on Deadline, a beloved family home full of memories, secrets, and a horrifying mystery.

9-1-1. I need someone's hat, I need EMT.

She was found with an accident back over her head.

I could still hear her trying to breathe.

Carlos said that someone had broken into the house and murdered his mom.

The front door was wide open.

There may be an axe murderer on the looks.

Yes, sir. You know, we're telling anyone's the alert.

Carlos, if there's some suspicious...

What kind of kid is Carlos?

Perfect. She wanted Carlos to have a brother.

The younger brother. He was troubled.

We started seeing cars showing up at night.

I had a goat that disappeared about the same time all the cars were coming and going.

We were able to find a victim of the cell phone. We found all the cameras as well.

You can see the connected dots on footprints very easily.

The evidence is not going to lie.

What do you think happened in that house?

It was a normal day until it wasn't.

Here's Dennis Murphy with...

...Horr at the Lake.

The Lake in Northwest Florida is as much as secluded nature preserved as it is a haven for retirees.

...