A medical mystery was solved Friday: T.R. Knight won't be back on "Grey's Anatomy" next season.
"Leaving 'Grey's Anatomy' was not an easy decision for me to make. I am extremely grateful to have had the opportunity to play this character and will miss my fellow cast and crew very much," Knight said in a statement.
He also thanked fans for their support but conspicuously didn't mention series creator and executive producer Shonda Rhimes.
Knight, who played Dr. George O'Malley, had seen his role diminished this season and asked to be let out of a contract that still had three years to go. In the season finale, his character had been injured -- fatally, it appeared -- as he saved a woman from a bus collision.
Katherine Heigl's character, Dr. Izzie Stevens, also appeared to have an uncertain future after brain surgery in the May finale. But Heigl will return to the show, ABC said Friday.