Lester Holt

What happens next to Nick Reiner?

Thanks for the updates, Mike.

Thanks, Lester.

For our final story this week, we wanted to take a closer look at a type of crime scene analysis that is considered one of the most difficult there is, arson investigation.

Just a few months ago, we told you about the conviction of Paul Zumott, the California hookah bar owner who murdered his girlfriend and then set fire to her home in an attempt to cover up his crime.

It didn't work, thanks in part to the analysis of fire investigators at the scene.

It made us wonder what exactly goes into an arson investigation.

We asked Scott Coleman, chair for regional training for the California Conference of Arson Investigators, to give us the basics.

Scott, thanks so much for joining us.

Thank you.

Thanks for having me.

The Bureau of Alcohol, Tobacco, Firearms, and Explosives, which offers training to law enforcement around the country, they say that arsons can be notoriously difficult to prove.

Why is that?

I was going to ask you, that seems like a conflict that you're there to put out the fire, save lives.

At the same time, you may be inadvertently destroying critical evidence.

You've trained hundreds of firefighters to investigate fires.

What does a typical arson investigation look like?

How does it unfold?

We mentioned the case of Paul Zumott up top in this conversation.

He's the California man convicted of murder and arson.