No person shall be eligible to qualify for the office of prosecuting attorney who is not an attorney and counselor at law duly licensed to practice as such in the district courts of the state at the time he assumes office as prosecuting attorney. No prosecuting attorney shall hold any other county or state office during his term of office as prosecuting attorney provided, however, that a prosecuting attorney or a deputy prosecuting attorney may be appointed by the attorney general as a special assistant attorney general for the performance of duties pursuant to such appointment in any other county than the county in which such prosecutor or deputy prosecutor serves. Nothing in this section, as amended, shall be construed to authorize the appointment of a special assistant attorney general except upon the request in writing of the prosecuting attorney in the county in which such special assistant attorney general is to serve, nor shall this section authorize the appointment of a prosecuting attorney as special assistant attorney general without his consent.