The Mentalist season 3 episode 10
Episode title: Jolly Red Elf
The CBI pursues two lines of investigation when a Santa is murdered: Patrick Jane goes undercover in an AA group; and Rigsby and Van Pelt question members of an authentic Santa society. Meanwhile, following the demise of a person in custody at the CBI, J.J. LaRoche is brought in to question the team when it appears to be an inside job.
