Marg Helgenberger is returning to CSI this October for the show's 300th episode, CBS announced today. Her Catherine Willows character will reemerge when the current roster of CSIs investigate one of her old cold cases. Helgenberg left the show a year and a half ago, so it's not like it's been that long since we've seen Catherine, but okay. Maybe this means it's also time to bring back Gil Grissom (again)? Or to have Warrick return from from beyond the grave?