Oregon Revised Statutes Protection from Fire § 476.210

(1) The municipal fire marshals, fire department chiefs, constables and other officers referred to in ORS 476.060 shall investigate the cause, origin and circumstances of each fire occurring in their respective cities, villages or townships, by which property has been destroyed or damaged, and shall make an investigation to determine whether the fire was the result of carelessness or design. The investigation shall be commenced immediately after the occurrence of the fire. The State Fire Marshal may superintend and direct the investigation if the State Fire Marshal deems it necessary.

(2) The fire chief of every city, or rural fire protection district shall provide the State Fire Marshal with a full report of every fire occurring within the jurisdiction of the fire chief on a form provided or approved by the State Fire Marshal. Whenever the fire chief of every city under 200,000 population finds any fire is of undetermined or suspicious origin or involves a death or serious injury, the fire chief shall immediately notify the State Fire Marshal or a deputy state fire marshal and shall assemble all known facts and circumstances concerning the fire in an approved report form and shall submit such report to the State Fire Marshal, or the deputy state fire marshal assigned to the territory in which the fire originated. When evidence clearly indicates the cause of fire to be of incendiary origin, the fire chief shall also immediately notify the state, county or municipal police agency.

(3) This section shall not apply to forestlands under the jurisdiction of the State Forester.