The affidavit is pretty thorough, even before pulling his cell phone info.
"A Forest Service fire investigator determined the Cascade Fire was likely the result of arson. He also noticed that on a dirt road 150 to 200 yards from the fire, a man was struggling to free his car, a black Kia Soul, after the vehicle's rear had failed to clear a partially buried boulder."
If you're going to be a wildlands arsonist, best to find the proper vehicle.