Katherine Heigl "Grieves" Over Lost Grey's Anatomy Colleague

No, Katherine Heigl's not grieving over Isaiah Washington's career -- rather, the actress Monday was seen on the Los Angeles set of her hit ABC show, Grey's Anatomy, wearing a head wrap and dark clothes while filming a funeral scene for Dr. George O' Malley, departed star T.R. Knight's character.

Knight left the show earlier this year citing creative differences over his character's direction with the show's executive producer, Shonda Rhimes.