ignition, the living room would reach flashover, blowing out the window. >> the entire room becomes engulfed in flames because there's so much burning and so much hot gas that it's completely uninhabitable. >> but the police witnessed the window breaking five or six minutes after paul called the fire department. to roby, this meant that gasoline couldn't have been used to start the fire. >> he would have had a tough time actually getting to the front door without being engulfed in flames. that's one of the things our model showed. so, we look at the arson scenario and there is inconsistency after inconsistency. >> next, roby tested paul camiolo's story. paul said the fire started by accident with a cigarette or a match his mother had been using. at one minute, the fire would be about two feet tall and gathering strength.