1.  Unconditional release and discharge.  An individual committed to the custody of the Department of Corrections or a jail in execution of a sentence of imprisonment must be unconditionally released and discharged upon the expiration of that individual's sentence, as determined after the deductions afforded that individual under this chapter, except that release is subject to the following provisions.  

2.  Release of individual sentenced prior to effective date of Maine Criminal Code.  An individual in the custody of the Department of Corrections pursuant to a sentence imposed under the law in effect prior to May 1, 1976 must be released and discharged according to the law as it was in force prior to May 1, 1976 and such law continues in force for this purpose as if this Code were not enacted.