I was listening to Micheal Smerconish a few years back and the story of Cameron Todd Willingham in the New Yorker was being highlighted. I was glued to the radio, and in the end I read the story, there is also a segment of Frontline about it. I have been fascinated with the subject of fire investigation ever since or more errors in Fire Investigation ever since and even did a research paper on it in college. After hearing  the testimony about the fire I knew she was not guilty. Fire Investigation in this nation is a wild west thing with the level of expertise all over the place. Most of the old school beliefs have been totally debunked. This has been done by a handful of experts who admitted they were wong to but learned much in the aftermath of the East bay Fire. 
There are many, many innocent people in jail for arson the numbers prove it.