(1) Upon application of a member or his employer, but in no event before termination of state service, any member who has not attained the age of fifty-five (55) years may be retired by the administrative board created by this chapter, not less than thirty (30) and not more than ninety (90) days next following the date of filing the application, on a disability retirement allowance, provided that the Medical Board of the Public Employees’ Retirement System of Mississippi, after an evaluation of medical evidence, which may include a physical examination by the medical board, certifies that he is mentally or physically incapacitated for the performance of duty, that the incapacity is likely to be permanent, and that the sickness or injury was caused or sustained as a direct result of duty in the Highway Safety Patrol after July 1, 1958.

Any former uniformed highway safety patrolman who has had not less than two (2) years of prior service with the Highway Safety Patrol and who was disabled by wounds or accident in line of duty, and who has returned to duty with the Highway Safety Patrol, and who becomes a member of the Highway Safety Patrol Retirement System with prior years’ service credits as provided in this chapter, may, if his disability from his previous wounds or accident received in line of duty returns and he again becomes totally and permanently disabled, receive full benefits as a disability retirant for service-connected disability.

Upon the application of a member or his employer, any member who is not yet eligible for service retirement benefits and who has had at least five (5) years of creditable service may be retired by the administrative board, not less than thirty (30) and not more than ninety (90) days next following the date of filing the application, on disability retirement allowance, provided that the Medical Board of the Public Employees’ Retirement System of Mississippi, after an evaluation of medical evidence, which may include a physical examination by the medical board, certifies that he is mentally or physically incapacitated for the further performance of duty, that the incapacity is likely to be permanent, and that he should be retired. This disability need not be service-connected.

(2) Upon retirement for disability, a member shall receive a disability benefit equal to fifty percent (50%) of his average salary for the two (2) years immediately preceding his retirement, but not less than any retirement benefits for which he may be eligible at the date he is granted disability.

(3) Once each year during the first five (5) years following retirement of a member on a disability retirement allowance, and once in every period of three (3) years thereafter, the administrative board may, and upon his application shall, require any disability beneficiary who has not yet attained the age of fifty-five (55) years to undergo a medical examination, the examination to be made at the place of residence of the beneficiary or other place mutually agreed upon, by the Medical Board of the Public Employees’ Retirement System. If any disability beneficiary who has not yet attained the age of fifty-five (55) years refuses to submit to any medical examination provided for in this subsection, his allowance may be discontinued until his withdrawal of that refusal, and if his refusal continues for one (1) year, all his rights in that part of the disability benefit provided by employer contributions shall be revoked by the administrative board.

(4) If the medical board reports and certifies to the administrative board that the disability beneficiary is engaged in, or is able to engage in, a gainful occupation paying more than the difference between his disability benefit and the average compensation, and if the administrative board concurs in that report, the disability benefit shall be reduced to an amount that, together with the amount earnable by him, equals the amount of his average compensation. If his earning capacity is later changed, the amount of the benefit may be further modified; however, the revised benefit shall not exceed the amount originally granted or an amount that, when added to the amount earnable by the beneficiary, equals the amount of his average compensation.

(5) If a disability beneficiary under the age of fifty-five (55) years is restored to active service at a compensation not less than his average compensation, his disability benefit shall cease; he shall again become a member of the retirement system, and he shall contribute thereafter at the same rate he paid before disability. Any such prior service certificate on the basis of which his service was computed at the time of retirement shall be restored to full force and effect. In addition, upon his subsequent retirement he shall be credited with all creditable service as a member, including the period for which he was paid disability benefits.