'Mentalist' Sneak Peek: Closing In on Red John

"Patrick Jane" (Simon Baker) and The Mentalist force have been trying to discover the identity of a serial killer named "Red John" for the duration of the show. In the Season 6 premiere, it looks like Jane is closing in on unearthing the infamous anonymous killer.

As we see in the sneak peek of Sunday's season premiere, Patrick and "Teresa Lisbon" (Robin Tunney) head out to the desert on a tip from one of the men listed to potentially be Red John.

PICS: One Actor, Two Roles, One Movie

On the car ride through the desert, Teresa urges Patrick that they release the names of the seven men who they have narrowed down as potentially being Red John, which is met with caution from Patrick, who mandates that no one else find out about the suspects list.

"I shouldn't have even told you," Patrick says as Teresa worriedly looks at him.

After years of searching for Red John, who killed his wife and daughter, Jane has put himself into the mind of the notorious serial killer and seems within mere steps of catching up to him and his devious ways.

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His on-screen partner, Tunney revealed to ET on the set of The Mentalist that Red John will be found this season. She also previewed a change in the series' format.

"[It gets] more serialized, and we find Red John finally," she teased. "I think people are ready, after six years, for us to find him. The structure of the show is going to completely change. ... We've had a very traditional procedural...and this year it's a different template, which is exciting as an actor."

Watch the clip above for a sneak peek at tonight's Season 6 premiere of The Mentalist, which will air in its entirety Sunday at 10 p.m. on CBS.