The reason behind two of The Mentalist's main characters' upcoming departure may have slipped out.

Agents Grace Van Pelt (Amanda Righetti) and Wayne Rigsby (Owain Yeoman) are scheduled to make a midseason departure form the CBS show. While many suspected it had something to do with the capture of Red John, who we will see taken care of by the New Year, it in fact looks like it will be caused by the pairs growing relationship.

Their characters are an on-again, off-again couple who were very definitely back on by the end of last season," said an insider, according to the National Enquirer. "As the CBI chases down serial killer Red John in Sea­son 6, they decide to get engaged...and leave the Serious Crimes Unit."

In the wake of their departure, two new FBI agents will arrive on the scene - Kim Fischer and Nick Abbott. TV Line claims Fischer is an intelligent 30-something former Dallas homicide detective while Abbott is a West Point graduate and war veteran with a short temper.

Rockmond Dunbar has been cast as Abbot and is currently scheduled to appear in episodes 7, 8, and 9, according to Deadline.

The Mentalist will return to CBS on Sept. 29.

Tags: The Mentalist