Any update on whether Castle will be touching on the 3XK killer again? — Chase
The show is definitely keen on revisiting that story line, but it's all
about timing. "We're having talks about whether we're bringing him back
by the end of this season," executive producer Andrew W. Marlowe
says. "But we're still waiting to hear on Season 5. If we get the
Season 5 pickup, it's something that we might wait and make more of a
meal of next year."
Source: TV Guide