The Board of Trustees shall appoint the Executive Director of the State Retirement Agency. The Executive Director serves at the pleasure of the Board of Trustees. The Executive Director shall: be in charge of the State Retirement Agency; compile annually a comprehensive budget for submission to the Board of Trustees; and have the duties and functions that the Board of Trustees may delegate. The Executive Director shall employ a staff to carry out the administrative duties of the several systems. Except as provided in § 21–315 of this title, the compensation of the Executive Director and staff shall be as provided in the State budget. Except for employees described in paragraph (3) of this subsection, the employees are skilled service or professional service employees subject to the provisions of this article that govern skilled service or professional service employees. An employee is in the executive service, management service, or is a special appointment in the State Personnel Management System if: the employee holds a position that the Executive Director, with the approval of the Board of Trustees, designates as a professional or technical position that involves specialized skill, education, and knowledge; and the employee’s labor is predominantly intellectual rather than manual or physical. The Executive Director and the Chief Investment Officer and staff of the Investment Division of the State Retirement Agency shall comply with the policies that the Board of Trustees prescribes about conflicts of interest and personal investments. A document that must be executed by or for the Board of Trustees shall be signed: by the Executive Director of the State Retirement Agency; or in the absence or disability of the Executive Director, by another employee whom the Executive Director, with the approval of the Chairman of the Board of Trustees, designates in writing. If a countersignature is required, with the approval of the Chairman of the Board of Trustees, the Executive Director shall designate those employees of the State Retirement Agency who may sign.