Frank is originally seen sitting in a desert diner and enjoying a strawberry milkshake. It is later revealed that he is an extraordinarily prolific serial killer who dismembers his living victims in a custom made trailer, he dopes them with Ketamine and then dismembers them under a mirror so they have to watch the process. he collects a right rib bone from every victim.Gideon and the other members of the BAU first encounter Frank in a small town called Golconda, twice in ten years bodies missing a rib have been discovered just outside the minuscule town. Frank wastes no time making his presence and intentions known. He kidnaps the local sheriff and waits for the team to find him in the diner. He then stalls Gideon and Morgan until the town realizes that in addition to the sheriff he has their children.The sheriff is found in Frank's trailer along with the body of a teacher. Gideon is forced to allow a disturbed woman named Jane to go with Frank. Jane was one of Frank's first victims. He mistakenly believes that he loves her because when he tried to kill her she looked into his eyes and was at peace. Gideon explains to Frank and Jane that Frank is a sexual sadist and a psycopath incapable of feeling anything ever. Nonetheless Frank claims to love Jane. The two flee as Gideon and the team save the town's children.The second time Frank appears it is with a flourish. Gideon is running late to meet an old friend - Sarah - at his apartment, Frank gets there first and brutally murders her. Frank declares that he will continue to kill until Jane is returned to him. Gideon is on the run because the D.C. cops consider him a prime suspect in Sarah's death. Nevertheless with Garcia's help Gideon discovers that Frank was the only son of a German immigrant named Mary Brightkopf, she worked as a prostitute. Remembering a story Frank told Gideon about a woman who committed suicide in New York and wasn't found for a year the team tracks down Frank's mother's address and find her mummified body lying in her bed surrounded by bouquets of flowers.It turns out that Frank and Jane fought and Jane declared that Gideon was right about him. Frank tried to kill Jane and she ran away seeking Gideon.Frank hunts down and kills one of the victims that Gideon saved in an earlier episode. He then kidnaps a young girl Gideon saved from being bludgeoned to death by a child serial killer. Frank leaves a note in the first victim's hand stating 7 am Union Square station. When the team finds Mary's body they also find Frank's hostage.Gideon meets Frank at the station with Jane and Hotchner. Jane allows Frank to talk her into running away with him again since he once again promises not to kill if he has her. Gideon and Hotchner try to stop them but Frank takes Jane's arm, together they run and jump in front of an incoming train.Due to Frank's actions and Gideon's own guilt and loss of faith Gideon later resigns from the BAU. Show less «