Except as provided in Section 8-1-115 and subject to the doctrine of constructive trust ex maleficio, the right of a person to retirement allowance or to the return of contributions, a retirement allowance itself, any optional or death benefit, or any other right accrued or accruing to a person under the provisions of this chapter, and the monies of the system are exempted from any state or municipal tax, except the taxes imposed pursuant to Chapters 6 and 16 of Title 12, and exempted from levy and sale, garnishment, attachment, or any other process, and are unassignable except as specifically otherwise provided in this chapter.