As the Red John story line wraps up on The Mentalist, the CBS show has a lot of small clues that need to be sorted out.

After chasing the notorious serial killer across six seasons, Patrick Jane (Simon Baker) and Teresa Lisbon (Robin Tunney) have accumulated a small pile a breadcrumbs that help to identify the culprit. However, some of these minute references still need to be explained.

'The Mentalist' Patrick Jane Leaves Lisbon VIDEO, Borrows Her Gun to Meet Red John PHOTO

For instance, in the few meetings Jane as Lisbon have had with Red John, why has the killer's voice never matched up with any of their suspects?

"We definitely will deal with that, and I think it's done in a really, really great way that's going to be coming up in [Episode 8]," said Mentalist writer Ken Woodruff, according to TV Guide. "We were very aware of that and conscious of it going forward and in dealing with Red John and [his] voice and all that stuff. So it definitely pays off, and faithful viewers will, I think, be satisfied by it."

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A new behind the scenes featurette for this Sunday's climactic "Red John" episode depicts a scruffy looking Gale Bertram (Michael Gaston) using a payphone to contact Jane.

"Hello, Patrick. I don't have to use the funny voice, do I? You know who this is," Bertram tells Jane.

Although "The Great Red Dragon" scriptwriter Jordan Harper cautions that "there's always another twist" when it comes to The Mentalist, series creator Bruno Heller promises that fans will not be left with lingering questions about the show's most elusive character.

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"We have the answers and it's very important to us, for those people who have been following us from the start, to reveal not in a series of cryptic moments that leave a lot of questions begged," Heller told The Hollywood Reporter. "We're going to tell the story and explain who Red John is and what happened and what is going to happen as clearly as possible because the audience deserves that."

The Mentalist airs Sundays at 10 p.m. on CBS. Check out the latest trailer for "Red John" by clicking the video below.

Tags: The Mentalist CBS television