began by interviewing's soon to be ex-husband, paul novak. >> what happened in the interview as far as the questions they asked you, how they treated you? >> they asked me about catherine's whereabouts, if they she had anywhere friends at the time, who would be in the house, and utilities in the house that would've had a problem, things like that. >> the interview was routine, but the investigation was not. firefighters cannot figure out what ignited the blaze. they check the wiring, the appliances, the pilot stove, the propane tanks, nothing conclusive. but then, things changed. the da brought in a specialist, a forensic pathologist to do a second autopsy a few days later. and the results this time told a different story. >> we knew she did not die in that fire, she died before the fire. >> the second pathologist discovered there was no carbon monoxide in catherine's blood or soot in her lungs.