07/10/2012 08:59 am ET

'Criminal Minds' Season 8: Jeanne Tripplehorn Is Alex Blake

When "Criminal Minds" Season 8 kicks off this fall, Jeanne Tripplehorn will be a major presence. The "Big Love" actress is joining the series as a replacement for Paget Brewster. The actress, who played Emily Prentiss, left at the end of Season 7.

According to CBS, Tripplehorn will play Alex Blake. Executive producer Erica Messer told TV Guide Tripplehorn's character has a history with the bureau, her specialty is linguistics and she has a history with Reid (Matthew Gray Gubler).

"In addition to being a supervisory special agent, she also is a professor at Georgetown University, and Reid has even guest-lectured at her forensic linguistics class before," Messer said. "So they have a nice professional history together."

Look for "Criminal Minds" Season 8 to kick off a few months after the Season 7 finale. Prentiss has transferred and the premiere will see Morgan (Shemar Moore) and Garcia (Kirsten Vangness) meeting Alex Blake for the first time.

The Brewster-Tripplehorn swap isn't the first "Criminal Minds" cast shake-up. Mandy Patinkin left the series after Season 2 and Brewster and A.J. Cook both left the series during Season 6 only to return amid fan outcry. Cook and Brewster's characters were replaced by Rachel Nichols' character Ashley Seaver, but viewers didn't quite take to the character. Messer told TV Guide she's worried about potential backlash.

"Prentiss was such a huge presence on the series and what helps everyone out a little bit is that it was her choice to go. It was actually Paget's choice to leave, and then we wrote in that it was Prentiss's choice to leave," she said. "That helps when the actual off-screen backstory can mimic what's happening on-screen."

"Criminal Minds" Season 8 returns to CBS this fall.

For more on Tripplehorn's new character, click over to TV Guide.

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