Wyo. Stat. § 7-5-303
The district judge granting the petition to convene a state grand jury shall impanel the state grand jury from a base jury list for the state compiled by the supreme court. The district court judge may specify that the base jury list for the state not include the names of jurors from every county within the state to limit juror expense and inconvenience of travel. A state grand jury shall be composed of twelve (12) persons, but not more than one-half (1/2) of the members of the state grand jury shall be residents of any one (1) county. The members of the state grand jury shall be selected by the court in the same manner as jurors of county grand juries and shall serve for one (1) year following selection unless discharged sooner by the district judge.
W.S. 7-5-303