I'll put my question here so everyone can see =).
In my book, the MC and his family lose their home to a fire. The cause is determined to be arson but no evidence was left behind (no finger prints, nada). First off, is it possible not to leave evidence behind in an arson fire? And in the story it's been 8 months and the three suspects they had weren't the arsonist(s)...I know who did it =), but is it normal to go 8 months with no arrests? And once they do catch the person, what's the usual procedure to get them in jail and how long would they be in jail for. The folks who did it are 18 and 19 years old.
I'm not an expert, but since I did lose my house in a fire two years ago, I can tell you a couple of things about it.
First of all, the way they determined that my house wasn't burned down purposefully by someone is using dogs to sniff the area. They have dogs that can sniff for gasoline and other things that can start a fire and since they found none of that, they knew that the fire was probably not started by someone.
The more a house burns down, too, the harder it is to piece together what happened. All the rooms in my house were on fire in some way, so they can't say definitively, for sure, what happened. So I'd say it's definitely possible for a house to burn enough that it's difficult to say what happened.
But I know point of origin is important, too. The point of origin in my house was the middle of the living room. They usually try to figure out what things were in that area to guess what could have caused the fire.
And also what's important to them is how fast the flames went up. My house went up in flames extremely quickly, so they think it was electrical wiring because that can go up fast. But so can arson if someone put gasoline all over the house or something. While something else, like a fire that started on the stovetop wouldn't necessarily spread as fast.
I don't know a whole lot because they kept us shielded from a lot of it, but that's what I know based on them talking to me.
EDIT: Oh and I don't know how it is for everyone, but they waited six months before they would officially speak to us about what happened. These investigations can definitely go a long time.