Tennessee Code Title 68. Health, Safety and Environmental Protection § 68-102-149

(a) It is lawful for the state fire marshal provided for in § 68-102-112, and such deputies as the fire marshal may designate who are full-time salaried employees of this state, to carry a pistol or side arm while on active duty in order to protect their own lives and to effectuate the purposes of their responsibilities in investigating cases of arson or suspected arson.

(b) It is lawful for municipal fire investigators who have been authorized by the chief of the municipal fire department or the director of fire services to conduct investigations relative to the cause and origin of fires and/or arson investigations to carry a pistol or side arm while on active duty in order to protect their own lives and to effectuate the purposes of their responsibilities in investigating cases of arson or suspected arson. For the sole purpose of being able to carry a pistol, such investigators shall comply with the requirements of § 39-17-1315(a).

(c) It is lawful for salaried county fire investigators who have been authorized by the chief of the county-wide fire department or the director of fire services to conduct investigations relative to the cause and origin of fires or arson investigations to carry a pistol or side arm while on active duty in order to protect their own lives and to effectuate the purposes of their responsibilities in investigating cases of arson or suspected arson. For the sole purpose of being able to carry a pistol, such investigators shall comply with the requirements of § 39-17-1315(a).