Wyoming Statutes Title 6. Crimes and Offenses § 6-2-101. Murder in the first degree;  penalty

(a) Whoever purposely and with premeditated malice, or in the perpetration of, or attempt to perpetrate, any sexual assault, sexual abuse of a minor, arson, robbery, burglary, escape, resisting arrest, kidnapping or abuse of a child under the age of sixteen (16) years, kills any human being is guilty of murder in the first degree.

(b) A person convicted of murder in the first degree shall be punished by death, life imprisonment without parole or life imprisonment according to law, except that a person convicted of murder in the first degree who was under the age of eighteen (18) years at the time of the offense shall be punished by life imprisonment.

(c) A person convicted of murder in the first degree in a case in which the state seeks the death penalty shall be sentenced in accordance with the provisions of W.S. 6-2-102.  In all other cases, including any case in which the state has determined not to seek the death penalty at any stage of the proceeding, the judge shall determine the sentence of life imprisonment without parole or life imprisonment taking into consideration any negotiated plea agreement and any evidence relevant to a determination of sentence which the court deems to have probative value.