Miss. Code § 21-31-9
It shall be the duty of the civil service commission to make suitable rules and regulations not inconsistent with the provisions of Sections 21-31-1 through 21-31-27. Such rules and regulations shall provide in detail the manner of conducting examinations, appointments, promotions, transfers, reinstatements, demotions, suspensions and discharges, and may also provide for any other matter connected with the general subject of personnel administration, and which may be considered desirable to further carry out the general purposes of Sections 21-31-1 through 21-31-27. It shall have the power to conduct investigations, and make reports on all matters touching the enforcement and effect of the provisions of Sections 21-31-1 through 21-31-27, and the rules and regulations prescribed hereunder. The commission shall have the power to investigate all complaints which must be reduced to writing, subpoena witnesses, administer oaths, and conduct hearings.
Miss. Code § 21-31-9