Jane Posner is an incidental character who appeared in The Itch.
Little is known about Jane's personal life, other than she suffers from Morgellons syndrome, which led her to believe there were fibers inside of her body, which she felt. Numerous attempts at treatment failed for her, leading her to become embittered about life. As a result, she developed paranoid beliefs that society was corrupted. She began attending a Morgellons support group led by Lisa Randall, whom she befriended to the point where Lisa would frequently visit her after the group's meetings were over.
Jane is first seen attending the support group, where she tells her story about her sickness, then goes on a rant against society and the government, which impresses Leo Jenkins. At the end of the meeting, Leo introduces himself to her. Later, they go to a restaurant and have a conversation about their sicknesses. Afterwards, they both go to Jane's apartment, where she allows Leo to take a sample of her blood and examine it. Then, they both kiss and go to sleep. The next morning, they are awakened by Lisa knocking on her front door. When Leo tells Jane to get rid of Lisa, she tells him that Lisa is alright, but he claims that she is one of them. Suddenly, they hear Lisa talking on the phone with the BAU. Leo promptly tells Jane that he will take care of it. Later, Rossi and Kate storm into Jane's apartment and ask where Leo is, but she calmly replies that he is gone and they are not going to find him.
Jane is taken to the police station, where she is interrogated by Kate and JJ. When they ask her about Leo's whereabouts, she refuses to tell them because she knows they will kill him. They reply that they don't want to and they are his only hope to get the help he needs, but Jane doesn't believe them and reiterates Leo's claim that the FBI tried to kill him once with a vaccination, unintentionally shedding a detail of his past. After Leo is arrested, JJ takes Jane back to her house. She continues to think that the FBI ruined her life and thinks that the BAU killed Leo and used her. JJ tells her that she is not an accessory as she didn't know what Leo was doing, and that they didn't kill Leo. She also tells her that she had a job to do and instructs her to testify against Leo. Jane refuses and accuses that the U.S. government is corrupt. JJ tells Jane that Leo abducted Lisa and was going to kill her, but she doesn't believe her again and shuts the door in front of her.