David Muir

Three of the girls were just totally not identifiable.

They were burned too much.

As soon as the Austin Police Department realized the scope of what they were dealing with, they called in extra investigators to help them.

Specifically, the FBI arrived at the scene, the ATF arrived at the scene.

It was an uphill battle to begin with, the processing of that crime scene.

Everything gets doused with water.

Because they did such a good job in putting the fire out, a lot of our evidence was destroyed.

There was evidence of sexual assault at the crime scene on the victims as well.

So all four girls were nude, and their clothing had been used to tie each other up.

They also took DNA from those victims.

So part of your standard sexual assault kit at an autopsy, besides swabs, is you also would take fingernail clippings.

For that very reason, because you think if a woman's being sexually assaulted, there's a good chance she's going to fight back.

And the fact that we were able

to get any DNA and any evidence from this scene is pretty remarkable, especially given the year, 1991.

DNA really was not something we talked about back then.

Initially, it was thought that it was possibly a robbery gone wrong, a robbery that turned into a horrific murder because cash had been pulled out and there was some cash missing.

We're dealing with four beautiful teenage girls.

Two of them are sisters, Jennifer and Sarah Harbison, Amy Ayers, and Eliza Thomas.

Just beautiful girls.

And it's just a tragedy.