'The Killing' Season 3: Billy Campbell and Michelle Forbes not returning

"The Killing" will return to AMC for a third season without a few key characters.

The show, canceled and then un-canceled after two seasons, is set to make its way back to AMC in 2013, possibly with the help of Netflix. Stars Mireille Enos and Joel Kinnaman are expected to return as detectives Sarah Linden and Stephen Holder -- but some of the people they investigated won't be back.

Variety reports that Billy Campbell, who played Seattle City Councilman (and eventually mayor) Darren Richmond, won't be back for Season 3. Neither will Michelle Forbes and Brent Sexton, who played the parents of murder victim Rosie Larsen.

The changes seem to point to a new case for Linden and Holder to investigate -- which would make sense, since the Larsen murder was at long last resolved in the Season 2 finale.

There's no word yet on when Season 3 of "The Killing" will premiere. What do you think of the cast changes?