(1) Except as otherwise provided for a juvenile offender in subsection (2) of this section, every person who is:
(a)Convicted of first-degree murder shall be sentenced by the court to imprisonment for life in the custody of the Department of Corrections.
(b)Convicted of second-degree murder shall be imprisoned for life in the custody of the Department of Corrections if the punishment is so fixed by the jury in its verdict after a separate sentencing proceeding. If the jury fails to agree on fixing the penalty at imprisonment for life, the court shall fix the penalty at not less than twenty (20) nor more than forty (40) years in the custody of the Department of Corrections.
Miss. Code Ann. § 97-3-21