Neb. Rev. Stat. §§ 81-506
The chief of the fire department of every city or village in which a fire department is established, the mayor of every incorporated city in which no fire department exists, the town clerk of every organized township, or the county commissioner in every commissioner district in counties not under township organization without the limits of any organized city or village shall investigate or cause to be investigated the cause, origin, and circumstances of every fire occurring in such city, village, township, or commissioner district by which property has been destroyed or damaged. All fires of unknown origin shall be reported, and such officers shall especially make investigation and report as to whether such fire was the result of carelessness, accident, or design. Such investigation shall begin immediately after the occurrence of such fire, and the State Fire Marshal shall have the right to supervise and direct such investigation whenever he or she deems it expedient or necessary. The officer making the investigation of fires occurring in cities, villages, townships, or commissioner districts shall forthwith notify the State Fire Marshal and shall, within one week of the occurrence of the fire, furnish him or her written statement of all the facts relating to the cause and origin of the fire and such further information as he or she may call for.
Neb. Rev. Stat. §§ 81-506