Joann Fielding was the mother of Leroy Jethro Gibbs's deceased wife Shannon Gibbs and the grandmother of Gibbs's daughter Kelly Gibbs. She was a witness to a murder investigation. Much of her past remains unknown other than the fact that she avenged her dead daughter and granddaughter by killing a man associated with the Reynosa drug cartel and framed another member for the murder, the cartel that their murderer, Pedro Hernandez, was a member of.