"The Mentalist" Season 6, Episode 15, titled "White as the Driven Snow" airs Sunday, Mar. 23 on CBS. This is the swan song for two regular characters in the series. Their exits have been confirmed months ago, but fans are still hoping these two would stay. After seeing last week's episode, many fans are asking: Is Grace Van Pelt dead? Owain Yeoman teases fans.

Spoiler alert: This feature contains spoilers on The Mentalist Season 6, Episode 15, White as the Driven Snow. This is the last mentalista episode with Grace Van Pelt (Amanda Righetti) and Wayne Rigsby (Owain Yeoman).

"It's a very dynamic episode. I think our show pushed the envelope," Yeoman told TV Guide. The Mentalist 6x15 is likely to be heavy, as the entire episode focuses on Van Pelt and Risgby.

Richard Haibach (William Mapother), one of the fake Red John suspects listed by Patrick Jane, returns in The Mentalist Season 6, Episode 15. He is one of Patrick Jane's (Simon Baker) suspects in this week's highly sensitive case.

This report by TV Guide implies Van Pelt is still alive. But she is in the hands of unknown kidnappers. It has been widely speculated the Blake Association (Red John's group) is behind the kill chain attacking former CBI personalities. Is Haibach actually involved? The sneak preview seems to suggest he is guilty.

"There's lots of twists and turns, and there's a bit of a badass side to Rigsby," Yeoman teased fans. The actor also said filming this week's new (farewell) episode is "very exciting." The Mentalist Season 6, Episode 15 could be the official end (for real) of the Red John chapter. (Unless creator Bruno Heller develops something related to RJ's Blake Association.)

As for Amanda Righetti, fans will soon see her as a guest star on Chicago Fire and its spin-off Chicago P.D.

WATCH: The Mentalist Season 6, Episode 15 (CBS on YouTube)

The Mentalist Season 6 airs Sundays on CBS. Watch the full episode on CBS.com or On Demand.

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