the locals and by the attorneys involved in this case. >> when the defense team learned about steve avato's opinion that the fire was an accident, they conducted their own investigation and hired dr. rick roby, an expert on the science of fires. >> what makes it difficult is, fires burn up a lot of the evidence. >> roby studies fires while they're burning. to do this, he sets fires like this one in model rooms. fires progress differently depending on how they're set, the size of the room, airflow and hundreds of other considerations. all of this data is then entered into a computer. >> it's a fully 3d fire modeling software that actually allows you to model the development and growth of a fire in a building. >> for this assignment, roby and his staff built a virtual reality replica of the camiolo home. then they entered all known information about the fire into the computer. roby conservatively estimated that it would take at least one gallon of gasoline to create a pour pattern the size of the one found in the living room. five or six minutes after paul camiolo called the fire department,