12/09/2008 AT 12:00 AM EST
Seattle Grace is about to lose another doctor. Grey's Anatomy
star T.R. Knight
, who has played lovable intern George O'Malley since the show's debut, has asked producers to write him off the hit medical drama.
While details of his exit have yet to be ironed out, a source close to the situation says that it seems likely Knight's request will be granted and he will be released from his contract.
Recent reports that Knight has not been attending table-reads for upcoming episodes or that he had walked off the set and cleaned out his dressing room are inaccurate, a rep for Knight tells PEOPLE: "He has been there every day. He was at a table read yesterday. He hasn't said goodbye to anyone." The rep had no further comment on his possible exit.
Of speculation that Knight was still upset about former cast member Isaiah Washington
's alleged use of a homophobic slur about him -- which prompted Knight to reveal he was gay, and which some felt series creator Shonda Rhimes
took too long to rectify with Washington's dismissal -- a source familiar with Grey's
says it is false.
"The Isaiah stuff has no relevance at all," says the source. "T.R. doesn't even know why would mention it. It was so long ago."
So why does Knight, who remains a fan favorite, want to leave?
"Have you seen the show lately?" says the source. Knight has received little screen time this season, with the show focusing on controversial storylines
like the romance between Katherine Heigl
's Izzie and her long-dead lover, Denny.
"It's time to move on," says the source. "It just feels like this is the right time to go."
News of Knight's possible exit, first reported by EW.com
, comes after Grey's made headlines
last month when actress Brooke Smith
, who played Dr. Erica Hahn, was abruptly let go from the show.
ABC had no comment.