Miss. Code § 21-29-35
Upon application of a member in service of the employer, any member who has become totally and permanently incapacitated for duty as the natural and proximate result of the actual performance of duty of the employer, without wilful negligence on his part, may be retired by the board on a duty disability retirement allowance effective thirty days after the filing of an application in writing with the board. However, the physician or physicians selected by the board to examine the member shall certify that such member is presumably permanently and totally disabled from engaging in any gainful occupation for compensation or profit, that under the facts as to the cause of disability, as certified by the board, the member's disability could have with reasonable probability resulted, in such physician's opinion, and that such member should be retired.
Miss. Code § 21-29-35