(1) A person who has pled guilty to or been convicted of first degree felony aggravated murder under Section 76-5-202 shall be sentenced by the court.
(2)
(a) The sentence under this section shall be:
(i) life in prison without parole; or
(ii) an indeterminate prison term of not less than 25 years and that may be for life.
(b) Subsection (2)(a)(i) does not apply if the person was younger than 18 years of age at the time the offense was committed and was sentenced on or after May 10, 2016.