PG & E power lines have caused the deadliest fire in California, say investigators

"It was the topography, it was the intensity of the fire and its footprint, its size," said Mohler. "A fire investigation is very, very methodical and takes a lot of time. Our investigators do not have the opportunity to be right at 80%, we have to be 100% right, and it's about closing the doors of the victims and the survivors of the fires. "