Got this from EW Ask Ausiello Spoliers
http://ausiellofiles.ew.com/2010/03/24/ask-ausiello-spoilers-bones-house-gossip/ Question: Didn’t expect to see Alex leaving again on Law & Order: SVU. Will she return this season? -Mark
Ausiello: Nope, she’s done for the season. That’s not to say she won’t be back next season though.