Lester Holt

And what's the possible sentence in a case like this if Gonzalez is in fact convicted?

He faces up to two years in prison.

Finally, we head to Los Angeles, where Nick Reiner, the man charged with killing his parents, Michelle and Rob Reiner, was set to be arraigned on Wednesday, but that didn't happen.

Tell us why plans changed.

Jackson gave his reasons at a press conference.

Let's hear what he had to say.

So what now?

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?