I guess that who determines the cause depends on what part of the world you are in.
Here in our city both the arson task force (trained PD detectives and Fire dept loss prevention inspectors ) and the Provincial Fire Commissioner's office investigate fires to determine the cause. In the rural areas the Fire Commissioner's office does the investigation with help from the local volunteer departments.
I believe there is a tax paid by the insurance companies based on the amount of property insurance they sell in Manitoba to fund the commissioner's office.
