During its fourteen-year run, "Dallas" saw several actors appearing in supporting roles. Among the most notable are Mary Crosby (seasons 3–4 and 14) as Sue Ellen's scheming sister Kristin Shepard (also portrayed by Colleen Camp for two second-season episodes), who has an affair with J.R. and is revealed to be the one who shot J.R. in the "Who shot J.R.?" storyline; Jared Martin (seasons 3–6, 8–9, and 14) as Sue Ellen's cowboy lover, and Clayton's foster son, Steven "Dusty" Farlow; Leigh McCloskey (seasons 4–5, 8 and 12) as medical student Mitch Cooper, Lucy's husband; Audrey Landers (seasons 4–8 and 12–13) as Mitch's sister Afton Cooper, an aspiring singer and Cliff's longtime fiancée; stage actress Priscilla Pointer (seasons 4–6) as Rebecca Barnes Wentworth, Pam's and Cliff's estranged mother; Morgan Brittany (seasons 5–8 and 11) as Rebecca's daughter, Katherine Wentworth, Cliff's and Pam's crazy half-sister who falls madly in love with Bobby; Lois Chiles (seasons 6–7) as Holly Harwood, J.R's ally and eventual lover; John Beck (seasons 6–7 and 9) as Mark Graison, Pam's beau after her first divorce from Bobby; Miss USA winner Deborah Shelton (seasons 8–10) as model Mandy Winger, longtime mistress of J.R.; Jenilee Harrison (seasons 8–10) as Jack Ewing's sister and Cliff's wife Jamie Ewing Barnes; and Andrew Stevens (seasons 11–12) as Casey Denault, a young hustler who works for J.R., romancing Lucy in order to get to her money.