19-20-303. Inactive membership. Any person's active membership in the retirement system terminates, but the person is an inactive member, when the person:
(1) ceases to be employed in a capacity that allows membership and the person has 5 or more years of creditable service in the retirement system;
(2) ceases to be employed in a capacity that allows membership and the person has less than 5 years of creditable service in the retirement system, but the loss of capacity to be a member was caused by a personal illness determined by the retirement board to be a disability or was caused by service in the armed forces of the United States, which includes the army, navy, marine corps, air force, and coast guard, or by service in the American red cross or merchant marine during time of war; or
(3) has 5 or more years of creditable service and becomes a member of any other retirement or pension system supported wholly or in part by the money of another government agency, except the federal social security retirement system, and the membership in the other retirement system would allow credit for the same employment service in two retirement systems. However, a person may not be excluded from active membership solely because the person is receiving or is eligible to receive retirement benefits from another retirement system.