in the season 1 finale In October 2006, Washington allegedly insulted Knight with a homophobic slur, during an on-set altercation with Dempsey, and ABC terminated Washington's contract at the end of season 3. Washington returned for a guest appearance in season 10. At the conclusion of season 3, Walsh departed the show to pursue the Grey's Anatomy spin-off, Private Practice, but continues to make guest appearances. Chyler Leigh joined the cast as a main character in season 4 as Dr. Lexie Grey, Meredith's half-sister. Leigh had appeared as a guest-star in the final 2 episodes of season 3. On the selection of Leigh for the role of Lexie, Rhimes said: "Chyler stood out ... It felt like she could be Meredith's sister, but she had a depth that was very interesting." Dr. Erica Hahn (Brooke Smith), who first appeared on Grey's Anatomy in season 2, returned as a series regular in season 4. Shortly after the announcement that Smith would be a regular member of the cast, Entertainment Weekly Michael Ausiello, reported that her character, Hahn, would depart from Grey's Anatomy on November 6, 2008. E! Online Kristin Dos Santos asserted that Smith's dismissal from the show had been forced by the ABC network, as part of an attempt to "de-gay" Grey's Anatomy. Rhimes countered these claims, saying that "we did not find that the magic and chemistry with Brooke's character would sustain in the long run". Season 5 introduced actor Kevin McKidd (Dr. Owen Hunt), who was signed as a series regular after originally being cast for a specific story-arc. In addition, Jessica Capshaw (Dr. Arizona Robbins) was originally introduced for a 3-episode arc, but her contract was extended until the end of the season; she became a series regular in the sixth season. Knight departed the show at the conclusion of season 5, citing an unhappiness with the development and lack of screen-time for his character. Directly following Knight's departure, Entertainment Weekly reported that Heigl had not returned to the set as scheduled after her maternity leave. It was later confirmed that Heigl would not return to the show at all. Kim Raver, who was cast as recurring character Dr. Teddy Altman in season 6, was given star billing later in the season. Sarah Drew (Dr. April Kepner) and Jesse Williams (Dr. Jackson Avery), who both made their series debuts as recurring characters in the sixth season, and