Article in Irish Times UK from Lisbon.
Sounds like RJ could be a main character or at least someone very unexpected
http://www.independent.ie/woman/celeb-news/tunney-shocked-at-red-john-reveal-29707739.html
The unveiling of the serial killer - the nemesis of mentalist Patrick Jane (played by Simon Baker) - is set to be revealed in the upcoming sixth season of the US show.
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"I was surprised, and had I been Red John, I would have been equally surprised," she said.Robin, who plays Senior Special Agent Teresa Lisbon on the show, admitted she was kept in the dark until the episode.
"I did not know at the beginning of the season. We're a bit ahead of you as far as filming goes, and yes, the audience will find out who Red John is," she continued, adding: "It's been exhausting. That's all I'll say."The 41-year-old laughed off rumours that her character is the cold-blooded murderer."Some days when you're bored and you want to feel badly about the show, you read things about yourself on the internet. It never ends well, like a Shakespearean lesson," she said.
"I was reading on one of the sites that 'Maybe Lisbon is Red John', and someone else said: 'Don't be ridiculous. There's no way that Lisbon is Red John'. And I'm like: 'Wait a minute!' I took umbrage at the idea that it was a sexist thing - a woman can be a serial killer."With the big reveal happening, Robin admitted she has signed up for one more series, saying: "We don't know; there's been a really interesting evolution. Simon and I are both signed up for seven years so we have one more year on our contracts."The sixth series of The Mentalist starts on Channel 5 on October 29