(A) Investigation of fires generally.
(1) The Legislative Authority may invest any officer of the fire or police department with the power, and impose on him or her the duty, to be present at all fires, investigate the cause thereof, examine witnesses, compel the attendance of witnesses and the production of books and papers, and to do and perform all other acts necessary to the effective discharge of such duties.
(2) The officer may administer oaths, make arrests, and enter for the purpose of examination any building which, in his or her opinion, is in danger from fire. The officer shall report his or her proceedings to the Legislative Authority at such times as are required.
(R.C. § 737.27)
(B) Investigation of major fires.
(1) The Fire Chief, or the Fire Prevention Officer, shall investigate the cause, origin, and circumstances of each major fire, as determined by the rules of the State Fire Marshal, occurring in the municipality 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 within two days, not including Sunday, if the fire occurred on that day. The State Fire Marshal may superintend the investigation.
(2) An officer making an investigation of a fire occurring in the municipality shall notify the State Fire Marshal, and within one week of the occurrence of the fire shall furnish him or her a written statement of all facts relating to its cause and origin, and other information as is required by forms provided by the State Fire Marshal.
(3) In the performance of the duties imposed by this chapter, the Fire Chief or Fire Prevention Officer, at any time of day or night, may enter upon and examine any building or premises where a fire has occurred, and other buildings and premises adjoining or near thereto.
(R.C. § 3737.24)