Deborah Roberts

We've told the public very clearly from the beginning that we believe it was a targeted attack.

They said, oh, this was a targeted attack, nothing to worry about.

And my first question was, but you don't have anybody.

That means there's somebody still out there.

The investigation grew massively.

We were trying to get every piece of video footage from that day from every surveillance camera in town captured from that night.

Right across the street from Zanna's bedroom is a house.

They have surveillance footage of a white Hyundai Elantra circling the house in the early morning hours of November 13th.

We quickly realized that we had this white vehicle during this time leaving at a very fast, high rate of speed.

You can see it is burning out of that neighborhood.

So we believed at that point this was the vehicle of our subject.

So we narrowed it down to a 2011 to 2016 Elantra.

Believe it or not, when we ran Idaho registrations and just looking local, we had over 25,000.

The search to track down that car has no limits.

We are just wanting to talk to the individuals who are in that vehicle.

Investigators also have a crucial piece of evidence found at the crime scene left behind by the killer.

A sheath for a K-bar knife.

This knife sheath was found under Maddie's body in the bed.

Immediately it stood out because it was in stark contrast to the entire house.

Once we know we had the DNA from the sheath, then we flew that to Othram and then they started to develop and work their part of it.