Kimball Cho is a character played by actor Tim Kang on The Mentalist . Cho is a tough but dedicated C.B.I. (California Bureau of Investigation) agent. An ex-Marine, Cho is very much by the book and rarely smiles. His partner is Wayne Rigsby.Cho enters into a romantic relationship with Summer Edgecombe, one of his informants. The relationship ends up being very short-term, although Cho and Edgecombe still remain friends.With the dissolution of the CBI, Cho joins the FBI, an ironic twist as he brawled with FBI agents after the accidental killing of Luther Wainwright.