A. If the state has filed a notice of intent to seek the death penalty and the defendant is convicted of first degree murder, the trier of fact at the sentencing proceeding shall determine whether to impose a sentence of death in accordance with the procedures provided in this section. If the trier of fact determines that a sentence of death is not appropriate, or if the state has not filed a notice of intent to seek the death penalty, and the defendant is convicted of first degree murder pursuant to section 13-1105, subsection A, paragraph 1 or 3 and was at least eighteen years of age at the time of the commission of the offense, the court shall impose a sentence of natural life. If the defendant was under eighteen years of age at the time of the commission of the offense or if the defendant is convicted of first degree murder pursuant to section 13-1105, subsection A, paragraph 2, the court shall determine whether to impose a sentence of life or natural life.
B. Before trial, the prosecution shall notice one or more of the aggravating circumstances under section 13-751, subsection F.
C. If the trier of fact finds the defendant guilty of first degree murder, the trier of fact shall then immediately determine whether one or more alleged aggravating circumstances have been proven. This proceeding is the aggravation phase of the sentencing proceeding.
D. If the trier of fact finds that one or more of the alleged aggravating circumstances have been proven, the trier of fact shall then immediately determine whether the death penalty should be imposed. This proceeding is the penalty phase of the sentencing proceeding.
E. At the aggravation phase, the trier of fact shall make a special finding on whether each alleged aggravating circumstance has been proven based on the evidence that was presented at the trial or at the aggravation phase. If the trier of fact is a jury, a unanimous verdict is required to find that the aggravating circumstance has been proven. If the trier of fact unanimously finds that an aggravating circumstance has not been proven, the defendant is entitled to a special finding that the aggravating circumstance has not been proven. If the trier of fact unanimously finds no aggravating circumstances, the court shall then determine whether to impose a sentence of life or natural life on the defendant pursuant to subsection A of this section.
F. The penalty phase shall be held immediately after the trier of fact finds at the aggravation phase that one or more of the aggravating circumstances under section 13-751, subsection F have been proven. A finding by the trier of fact that any of the remaining aggravating circumstances alleged has not been proven or the inability of the trier of fact to agree on the issue of whether any of the remaining aggravating circumstances alleged has been proven shall not prevent the holding of the penalty phase.
G. At the penalty phase, the defendant and the state may present any evidence that is relevant to the determination of whether there is mitigation that is sufficiently substantial to call for leniency. In order for the trier of fact to make this determination, regardless of whether the defendant presents evidence of mitigation, the state may present any evidence that demonstrates that the defendant should not be shown leniency including any evidence regarding the defendant's character, propensities, criminal record or other acts.
H. The trier of fact shall determine unanimously whether death is the appropriate sentence. If the trier of fact is a jury and the jury unanimously determines that the death penalty is not appropriate, the court shall determine whether to impose a sentence of life or natural life pursuant to subsection A of this section.
I. If the trier of fact at any prior phase of the trial is the same trier of fact at the subsequent phase, any evidence that was presented at any prior phase of the trial shall be deemed admitted as evidence at any subsequent phase of the trial.
J. At the aggravation phase, if the trier of fact is a jury, the jury is unable to reach a verdict on any of the alleged aggravating circumstances and the jury has not found that at least one of the alleged aggravating circumstances has been proven, the court shall dismiss the jury and shall impanel a new jury. The new jury shall not retry the issue of the defendant's guilt or the issue regarding any of the aggravating circumstances that the first jury found not proved by unanimous verdict. If the new jury is unable to reach a unanimous verdict, the court shall impose a sentence of life or natural life on the defendant.
K. At the penalty phase, if the trier of fact is a jury and the jury is unable to reach a verdict, the court shall dismiss the jury and shall impanel a new jury. The new jury shall not retry the issue of the defendant's guilt or the issue regarding any of the aggravating circumstances that the first jury found by unanimous verdict to be proved or not proved. If the new jury is unable to reach a unanimous verdict, the court shall impose a sentence of life or natural life on the defendant.
L. If the jury that rendered a verdict of guilty is not the jury first impaneled for the aggravation phase, the jury impaneled in the aggravation phase shall not retry the issue of the defendant's guilt. If the jury impaneled in the aggravation phase is unable to reach a verdict on any of the alleged aggravating circumstances and the jury has not found that at least one of the alleged aggravating circumstances has been proven, the court shall dismiss the jury and shall impanel a new jury. The new jury shall not retry the issue of the defendant's guilt or the issue regarding any of the aggravating circumstances that the first jury found not proved by unanimous verdict. If the new jury is unable to reach a unanimous verdict, the court shall impose a sentence of life or natural life on the defendant.
M. Alternate jurors who are impaneled for the trial in a case in which the offense is punishable by death shall not be excused from the case until the completion of the sentencing proceeding.
N. If the sentence of a person who was sentenced to death is overturned, the person shall be resentenced pursuant to this section by a jury that is specifically impaneled for this purpose as if the original sentencing had not occurred.
O. In any case that requires sentencing or resentencing in which the defendant has been convicted of an offense that is punishable by death and in which the trier of fact was a judge or a jury that has since been discharged, the defendant shall be sentenced or resentenced pursuant to this section by a jury that is specifically impaneled for this purpose.
P. The trier of fact shall make all factual determinations required by this section or the Constitution of the United States or this state to impose a death sentence. If the defendant bears the burden of proof, the issue shall be determined in the penalty phase. If the state bears the burden of proof, the issue shall be determined in the aggravation phase.
Q. If the death penalty was not alleged or was alleged but not imposed, the court shall determine whether to impose a sentence of life or natural life pursuant to subsection A of this section. In determining whether to impose a sentence of life or natural life, the court:
1. May consider any evidence introduced before sentencing or at any other sentencing proceeding.
2. Shall consider the aggravating and mitigating circumstances listed in section 13-701 and any statement made by a victim.
R. Subject to section 13-751, subsection B, a victim has the right to be present at the aggravation phase and to present any information that is relevant to the proceeding. A victim has the right to be present and to present information at the penalty phase. At the penalty phase, the victim may present information about the murdered person and the impact of the murder on the victim and other family members and may submit a victim impact statement in any format to the trier of fact.
S. For the purposes of this section:
1. "Trier of fact" means a jury unless the defendant and the state waive a jury, in which case the trier of fact shall be the court.
2. "Victim" means the murdered person's spouse, parent, child, grandparent or sibling, any other person related to the murdered person by consanguinity or affinity to the second degree or any other lawful representative of the murdered person, except if the spouse, parent, child, grandparent, sibling, other person related to the murdered person by consanguinity or affinity to the second degree or other lawful representative is in custody for an offense or is the accused.