Brenda Shettrick was the head of the CBI Media Relations unit. Her job includes liaising with media and leading outreach programs, among other public-facing efforts. She appears to have a good relationship with the CBI team and senior agents. During the season 3 finale, it is revealed that she is among Agent J.J. LaRoche's five suspects for the Todd Johnson murder, and while it was initially believed that CBI director Gale Bertram was the killer, FBI agent Craig O'Laughlin was revealed as Red John's accomplice and the true killer of Todd Johnson and Manuel Montero. In "Little Red Corvette," it is revealed that Brenda is Tommy Volker's friend in CBI who has been feeding him information on Lisbon's investigation of him and she doesn't enjoy working for him.
In Red and Itchy, it is revealed that Brenda is the information leak in the CBI, who was responsible for many high profile criminals getting away, and responsible for stealing J.J. LaRoche's tupperware container. She is caught in one of Jane's usual elaborate plans and arrested. In Green Thumb, her name was seen on a list of confirmed Blake Association members.