The Fire Marshal's Division investigates fires, burns, and serious injuries in the City of Monroe. Fire origin and cause investigations result in determinations such as incendiary, undetermined, accidental, and natural, following the guidelines of NFPA 921, Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA) sets the standards for scientific-based investigation and analysis of fire and explosion incidents. Since 2015, the Monroe Fire Department has had an inter-local agreement with the Union County Fire Marshal's Office that allows for mutual aid response between the two agencies. The Fire Marshal Division also receives support from the Monroe Police, NC State Bureau of Investigations, Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), NC Forestry Service, North Carolina Office of State Fire Marshal, and OSHA.