(1) Notwithstanding any other provision of law, the death penalty shall not be imposed upon any person who was under the age of eighteen years at the time of the commission of the crime.
(2) Notwithstanding any other provision of law, the death penalty shall not be imposed upon any person with an intellectual disability.
(3) As used in subsection (2) of this section, intellectual disability means significantly subaverage general intellectual functioning existing concurrently with deficits in adaptive behavior. An intelligence quotient of seventy or below on a reliably administered intelligence quotient test shall be presumptive evidence of intellectual disability.
(4) If (a) a jury renders a verdict finding the existence of one or more aggravating circumstances as provided in section 29-2520 or (b)(i) the information contains a notice of aggravation as provided in section 29-1603 and (ii) the defendant waives his or her right to a jury determination of the alleged aggravating circumstances, the court shall hold a hearing prior to any sentencing determination proceeding as provided in section 29-2521 upon a verified motion of the defense requesting a ruling that the penalty of death be precluded under subsection (2) of this section. If the court finds, by a preponderance of the evidence, that the defendant is a person with an intellectual disability, the death sentence shall not be imposed. A ruling by the court that the evidence of diminished intelligence introduced by the defendant does not preclude the death penalty under subsection (2) of this section shall not restrict the defendant's opportunity to introduce such evidence at the sentencing determination proceeding as provided in section 29-2521 or to argue that such evidence should be given mitigating significance.