Pardons are awarded by the Governor upon recommendation by the Parole Commission, and may be full, conditional, or partial. If pardon is denied, the petitioner may reapply after a reasonable time. Before making its recommendation to the Governor, the Commission shall cause a comprehensive investigation of the individual to be prepared by the Division of Parole and Probation for submission to it and to the Governor. Request for pardon may be initiated by petition or letter directed to the Parole Commission. Proof of successful completion of any parole or probation, or both, which may have been imposed, plus a reasonable length of satisfactory adjustment in the community beyond the maximum expiration date of sentence, is preferred for a favorable pardon recommendation.