Kenny Johnson, Robin Tunney Kenny Johnson, Robin Tunney

The Mentalist viewers will soon meet another man in Teresa Lisbon's life — but this time it's a man from her past.

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's Kenny Johnson has been tapped to play Greg Taybeck, the high school boyfriend and ex-fiancé of Lisbon (Robin Tunney), has learned exclusively. When Greg becomes involved in one of the CBI's cases, Lisbon is a bit rattled.

"I think it takes her longer to get to the bottom of the case because it's hard for her to see the thing clearly," creator and executive producer Bruno Heller tells us. "But it's her understanding of him and his character that helps solve the case."

Ultimately, the reunion will give Lisbon a moment to reflect on her life choices. "She ran away [from that relationship] to find a different life," Heller says. "So, she stops and has to reassess her life and look at the paths not taken. Her boyfriend has kids, and she doesn't. So, how does she feel about that?

See photos of the Mentalist cast