The right to a retirement benefit, district attorney emeritus salary, return of contributions, any optional benefit, or any other right accrued or accruing to any person under this chapter and the moneys in the fund are exempt from any state, county, or municipal tax, except as provided in Code Section 48-7-27; exempt from levy and sale, garnishment, attachment, or any other process whatsoever; and shall not be assignable, except as otherwise specifically provided for in this chapter.