If it is determined to be a homicide that occurred outside of Federal jurisdiction in the state of Wyoming, then you are correct about premeditation. His is the Wyoming legal statute for murder:
Wyoming Statutes
TITLE 6 - CRIMES AND OFFENSES
CHAPTER 2 - OFFENSES AGAINST THE PERSON
ARTICLE 1 - HOMICIDE
6-2-101. Murder in the first degree; penalty.
Universal Citation:
WY Stat § 6-2-101 (2014)
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.
And here are definitions of premeditatio:
The second element also requires the actor to have killed with “premeditation.”
Premeditation is the “thinking over, deliberating upon, weighing in the mind beforehand, resulting in a deliberate intention to kill which constitutes the killing murder in the first degree.” Parker v. State, 161 P. 552, 555 (Wyo. 1916). “
Premeditation need not have existed for any given length of time before the act, it being sufficient that it existed at the time of the act; and the intent and the act may be as instantaneous as successive thoughts.” Mattern v. State, 151 P.3d 1116, 1129-1130 (Wyo. 2007).
I believe this requirement for and definition of premeditation would be the same or similar under federal law if they take the case. My experience is on the enforcement side, so if we have any lawyers here, please feel free to correct me.