Gillette, WY – GILLETTE, Wyo. (AP) - A Gillette teenager will be in court this morning (Thursday) to face charges of his involvement in the killing of witness in a sex-assault case. Fifteen-year-old Michael Seiser is one of three people charged with murder in the November shooting death of 16-year-old Bryce Chavers. Authorities say they killed Chavers as a favor for 42-year-old Kent Proffit Senior. Proffit was scheduled for trial on charges that he'd sexually assaulted Chavers. Seiser is the first of the four to face a preliminary hearing. Also charged are 19-year-olds Jacob Martinez and Christopher Hicks.