(a) Except as provided in subsection (b) of this section, each employee of the Division of Criminal Justice and each public defender, assistant public defender and deputy assistant public defender in the Superior Court who is or becomes a member of the state employees retirement system shall receive full retirement credit and full credit for the vesting of pension rights for each year or portion thereof for which retirement contributions were or shall be paid while serving as a state’s attorney, an assistant state’s attorney, deputy assistant state’s attorney, prosecuting attorney, assistant prosecuting attorney, public defender or assistant public defender in the Superior Court, Circuit Court or Court of Common Pleas, irrespective of whether such service was on a part-time or full-time basis, provided he shall have made contributions to the State Employees Retirement Fund as provided by this chapter, for such service credit.

(b) Each such employee and each such public defender, assistant public defender and deputy assistant public defender who serves on a part-time basis, on and after July 1, 1985, shall receive retirement credit for such service on a percentage basis corresponding to the percentage that the amount of time spent in such service bears to full-time service in such position, as the percentage shall be determined by the commission, provided such individual shall have made contributions to the State Employees Retirement Fund as provided by this chapter, for such service credit.