Wyo. Stat. § 37-2-201
Whenever the commission shall determine to conduct an investigation of any matter provided for in W.S. 37-1-101 through 37-3-114 and 37-12-201 through 37-12-213, either with or without complaint as in such chapter provided for, it shall fix a time and place for a public hearing of the matters under investigation, and shall notify, by registered letter requiring receipt, the complainant, the persons complained of and such other persons, as it may deem proper, of such time and place of hearing, at least twenty (20) days in advance thereof. At the hearing held pursuant to such notice, the commission, commissioner or commission employee authorized by order of the commission to conduct such hearing, may take such testimony as may be offered, or as they may desire, and may make such other and further investigation as in its opinion, is desirable.
W.S. 37-2-201