(a) If a defendant is charged with capital murder, the county or district attorney shall file written notice if such attorney intends, upon conviction of the defendant, to request a separate sentencing proceeding to determine whether the defendant should be sentenced to death. In cases where the county or district attorney or a court determines that a conflict exists, such notice may be filed by the attorney general. Such notice shall be filed with the court and served on the defendant or the defendant’s attorney not later than seven days after the time of arraignment. If such notice is not filed and served as required by this subsection, the prosecuting attorney may not request such a sentencing proceeding and the defendant, if convicted of capital murder, shall be sentenced to life without the possibility of parole, and no sentence of death shall be imposed hereunder.

(b) Except as provided in Kan. Stat. Ann. §§ 21-6618 and 21-6622, and amendments thereto, upon conviction of a defendant of capital murder, the court, upon motion of the prosecuting attorney, shall conduct a separate sentencing proceeding to determine whether the defendant shall be sentenced to death. The proceeding shall be conducted by the trial judge before the trial jury as soon as practicable. If any person who served on the trial jury is unable to serve on the jury for the sentencing proceeding, the court shall substitute an alternate juror who has been impaneled for the trial jury. If there are insufficient alternate jurors to replace trial jurors who are unable to serve at the sentencing proceeding, the trial judge may summon a special jury of 12 persons which shall determine the question of whether a sentence of death shall be imposed. Jury selection procedures, qualifications of jurors and grounds for exemption or challenge of prospective jurors in criminal trials shall be applicable to the selection of such special jury. The jury at the sentencing proceeding may be waived in the manner provided by Kan. Stat. Ann. § 22-3403, and amendments thereto, for waiver of a trial jury. If the jury at the sentencing proceeding has been waived or the trial jury has been waived, the sentencing proceeding shall be conducted by the court.

(c) In the sentencing proceeding, evidence may be presented concerning any matter that the court deems relevant to the question of sentence and shall include matters relating to any of the aggravating circumstances enumerated in Kan. Stat. Ann. § 21-6624, and amendments thereto, and any mitigating circumstances. Any such evidence which the court deems to have probative value may be received regardless of its admissibility under the rules of evidence, provided that the defendant is accorded a fair opportunity to rebut any hearsay statements. Only such evidence of aggravating circumstances as the state has made known to the defendant prior to the sentencing proceeding shall be admissible, and no evidence secured in violation of the constitution of the United States or of the state of Kansas shall be admissible. No testimony by the defendant at the sentencing proceeding shall be admissible against the defendant at any subsequent criminal proceeding. At the conclusion of the evidentiary presentation, the court shall allow the parties a reasonable period of time in which to present oral argument.

(d) At the conclusion of the evidentiary portion of the sentencing proceeding, the court shall provide oral and written instructions to the jury to guide its deliberations.

(e) If, by unanimous vote, the jury finds beyond a reasonable doubt that one or more of the aggravating circumstances enumerated in Kan. Stat. Ann. § 21-6624, and amendments thereto, exist and, further, that the existence of such aggravating circumstances is not outweighed by any mitigating circumstances which are found to exist, the defendant shall be sentenced to death; otherwise, the defendant shall be sentenced to life without the possibility of parole. The jury, if its verdict is a unanimous recommendation of a sentence of death, shall designate in writing, signed by the foreman of the jury, the statutory aggravating circumstances which it found beyond a reasonable doubt. If, after a reasonable time for deliberation, the jury is unable to reach a verdict, the judge shall dismiss the jury and impose a sentence of life without the possibility of parole and shall commit the defendant to the custody of the secretary of corrections. In nonjury cases, the court shall follow the requirements of this subsection in determining the sentence to be imposed.

(f) Notwithstanding the verdict of the jury, the trial court shall review any jury verdict imposing a sentence of death hereunder to ascertain whether the imposition of such sentence is supported by the evidence. If the court determines that the imposition of such a sentence is not supported by the evidence, the court shall modify the sentence and sentence the defendant to life without the possibility of parole, and no sentence of death shall be imposed hereunder. Whenever the court enters a judgment modifying the sentencing verdict of the jury, the court shall set forth its reasons for so doing in a written memorandum which shall become part of the record.

(g) A defendant who is sentenced to imprisonment for life without the possibility of parole shall spend the remainder of the defendant’s natural life incarcerated and in the custody of the secretary of corrections. A defendant who is sentenced to imprisonment for life without the possibility of parole shall not be eligible for commutation of sentence, parole, probation, assignment to a community correctional services program, conditional release, postrelease supervision, functional incapacitation release pursuant to Kan. Stat. Ann. § 22-3728, and amendments thereto, or suspension, modification or reduction of sentence. Upon sentencing a defendant to imprisonment for life without the possibility of parole, the court shall commit the defendant to the custody of the secretary of corrections and the court shall state in the sentencing order of the judgment form or journal entry, whichever is delivered with the defendant to the correctional institution, that the defendant has been sentenced to imprisonment for life without the possibility of parole.