Wildfires like the Los Angeles blazes destroy so much, but they often spare some evidence of the cause of their ignition ...

difficulty expressing emotions and an interest in fire paraphernalia. Yet motives are often multiple and can be slippery to pin down. “We are still learning about the psychology of arson ...

So far, the probe is focusing on potential human causes, which could include arson, fireworks, unauthorized camping or a rekindling of an earlier fire, law enforcement sources said.

While the arson numbers are disconcerting, especially in the wake of the wildfires, the situation may be getting worse.

With fires recently scorching parts of Southern California ABC10 News looks into how fire investigations work.