Section 57.997 - Former sheriff may be employed as special advisor and purchase annuity1. Any person sixty-five years of age or older who was employed as a county sheriff prior to September 28, 1983, and who is not a member of the system, upon application to the board, presentation of proof of service as a county sheriff satisfactory to the board, and payment into the sheriffs' retirement fund of the amount hereafter provided in this section shall be appointed and employed by the board as a special advisor on law enforcement for life whose duties shall be to give opinions, orally or in writing, on law enforcement and related matters to the board, the county sheriff's office where the person last served as county sheriff, or to any department of state government with duties relating to law enforcement upon the request of such board, county sheriff's office or department of state government. The person shall pay into the sheriffs' retirement fund an amount actuarially determined to be sufficient to fund an annual annuity for himself for life of one thousand two hundred dollars or a lesser amount if he so desires. As compensation for serving as a special advisor on law enforcement he shall receive one hundred dollars per month or less, depending on the amount paid into the sheriffs' retirement fund, to be paid out of the sheriffs' retirement fund in the same manner and at the same time as retirement benefits are paid.2. Should a special advisor die before receiving compensation paid pursuant to this section totaling an amount equal to the amount paid into the sheriffs' retirement fund pursuant to subsection 1 of this section, an amount equal to the difference between the amount paid in and the total of all compensation amounts paid to him pursuant to this section prior to his death, with interest, shall be paid out of the sheriffs' retirement fund to any beneficiary designated by him. If no designation of beneficiary is made, the amount shall be paid to his estate.3. No person can be both a member of the system and a special advisor on law enforcement.