This is a good lead-in for what I'm sure would be a lengthy discussion on the consideration of circumstances in determining a fire's origin and cause. I know there are those that would say that you cannot consider circumstances when examining a scene; that the scene must speak for itself. But, a fire occurs within a set of surrounding circumstances that need to be considered for their relevance. Evidence of another crime may help to explain an ignition sequence. Witness or suspect statements may provide some context. I use the example of a trash can fire. If I light my cigarette, drop the match in the trash can and walk away, a fire occurs that looks a certain way. What is different about the scene if I drop the match after being told that I've been fired and walk out of the office cursing everyone and threatening retaliation? The actual fire scene will look the same (in some cases the timeline might be different), but the circumstances surrounding the event are worlds apart. That having been said, investigators need to be extremely cautious in overvaluing circumstances. Take as an example, two businesses owned by the same owner in a rural area with no physical connections and a mile apart. Both buildings are discovered to be on fire almost simultaneously. The two events are inextricably linked; you can't ignore the facts. But it doesn't mean that the owner set the fires (although further investigation is certainly warranted.)