Criminal Minds

A.J. Cook will return to Criminal Minds for one episode, a source tells TVGuide.com.

Check out photos of A.J. Cook

Cook, 32, is due back on the set this week to reprise her role as agent and media liaison Jennifer "JJ" Jareau for Paget Brewster's final episode.

"Heading back to Criminal Minds for @pagetpaget final episode," she tweeted Tuesday. "@GUBLERNATION [Matthew Gray Gubler] is directing. It's going to be GOOD/WEIRD/SAD!!!"

The actress, who was dropped from the procedural last summer for "creative reasons," exited in this season's second episode, as JJ was poached by the Defense Department.

It's unclear under what circumstances JJ is returning to the BAU. Brewster's exit arc kicked off last week when she was informed that a criminal she put away during her days with Interpol had escaped.

Brewster was demoted to appear in 17 out of 22 episodes this season and had the option to remain as a regular.

Criminal Minds: The top 8 JJ moments

Since Cook's departure, Minds has promoted recurring guest star Rachel Nichols to series regular.

Cook, meanwhile, has guest-starred on Law & Order: Special Victims Unit opposite Jeremy Irons and filmed a TV movie with Jennifer Morrison.

Are you glad JJ's coming back?