Tenn. Code § 8-619
Any attorney general as defined in § 8-618 may retire (a) at the age of seventy (70) upon twenty (20) years' service; (b) at the age of sixty-five (65) upon twenty-four (24) years of service; (c) at the age of sixty (60) upon thirty (30) years of service.
Provided that all persons who have served continuously in this state as assistant attorney general and attorney general for a period of time as much as twenty-one (21) years and who had reached the age of seventy-three (73) years on April 6, 1953, and who had been retired from said service prior to April 6, 1953, and was as much as seventy (70) years of age at the time of his retirement, and whose salary as such assistant attorney general and attorney general was paid entirely from the state treasury, shall be included as a person entitled to receive benefits from §§ 8-618 - 8-622 on same terms and conditions as those enumerated in said sections.
After September 1, 1958, if any attorney general as defined in § 8-618 should have a total of thirty (30) years service as such attorney general and/or as a member of either the state or teachers' retirement system, the last ten (10) years of which service shall have been as attorney general, such person shall be eligible to retirement, regardless of age, under §§ 8-618 - 8-622 and shall be given credit thereon for his services in such other retirement system: provided, that his reserve paid to such other retirement system shall be transferred to this retirement system.
T.C.A. § 8-619