If the attorney for the Commonwealth of any county or city is connected by blood or marriage with the accused, or is so situated with respect to such accused as to render it improper, in his opinion, concurred in by the judge, for him to act, or if such attorney for the Commonwealth of any county or city is unable to act, or to attend to his official duties as attorney for the Commonwealth, due to sickness, disability or other reason of a temporary nature, then upon notification by such attorney for the Commonwealth, or upon the certificate of his attending physician, or the clerk of the court, which fact shall be entered of record, the judge of the circuit court shall appoint from another jurisdiction an attorney for the Commonwealth or an assistant attorney for the Commonwealth, with the consent of such attorney for the Commonwealth or assistant, who is not authorized by law to engage in private practice for such case or cases, term or terms of court, or period or periods of time, as may be necessary or desirable, and the same to be forthwith entered of record. However, if the circuit court determines that the appointment of such attorney for the Commonwealth or such assistant attorney for the Commonwealth is not appropriate or that such an attorney or assistant is unavailable, or for other good cause, then the circuit court may appoint an attorney-at-law who shall be compensated pursuant to § 19.2-332. Such appointee shall act in place of, and otherwise perform the duties and exercise the powers of, such disqualified or disabled attorney for the Commonwealth, in regard to such case or cases, for the term or terms of the court, or the period or periods of time, for which the appointment and designation is made, or until the disqualified or disabled attorney for the Commonwealth shall again be able to attend to his duties as such. Nothing herein shall prevent a court from appointing as a special assistant attorney for the Commonwealth, without additional compensation, an attorney employed by a state agency when such appointment is requested by the attorney for the Commonwealth and the court determines such appointment will aid in the prosecution of a particular case or cases. An attorney for the Commonwealth or assistant attorney for the Commonwealth who is required by law to devote full time to his duties as such shall not receive additional compensation for services rendered on appointment pursuant to this section. However, such attorney for the Commonwealth or assistant may receive reimbursement for actual expenses incurred, as approved by the Compensation Board to be paid by the Compensation Board, provided such expenses are not otherwise reimbursed by the county or city which he is elected or appointed to serve or by the Compensation Board.