He is killed in the episode "Last Man Standing" by Agent Michelle Lee, and initially suspected of being a mole. Lee is, in fact, the mole, as Langer learns, and she kills him to preserve her cover. He was mentored by Gibbs at NCIS before joining the FBI and is transferred back to NCIS at Gibbs' recommendation. He works with Gibbs' team in the episode "Tribes", where he assists the team in tracking down a terrorist recruiter. Gibbs places his voided FBI agent ID card on a wall commemorating fallen personnel in the episode, "Collateral Damage", just as Gibbs is turning his suspicion back to Agent Lee. Special Agent Michelle Lee (Liza Lapira) first appears in the episode "Shalom". She is brought in between season three and four to bring the team back up to full strength following the departure of Gibbs. Following Gibbs' return early on in the season she is transferred to the legal department and is frequently seen delivering warrants to the team, also having a covertly intimate affair with the medical examiner's assistant, Jimmy Palmer. She returns to the series in season six as part of Gibbs' new team, but is reassigned after the first episode. It is revealed that she is a mole in NCIS who has accessed for a foreign power at least the Joint Chiefs' strategic battle plans for a potential Middle Eastern operation, if Israel's enemies were to once again make war upon her. Although Gibbs figures out gradually that she is a spy, and affirms his conclusions by inserting a picture of an agent she shot, as if he were the spy, on a barwall "Slain Heroes" wall ("Collateral Damage"), she is caught in the next episode "Cloak". However, when caught she claims that she was forced to trade government secrets because her daughter Amanda has been kidnapped. But Amanda, it turns out, is actually her sister. The deaths of their parents prompted Lee to raise Amanda as her child. In the episode "Dagger", after she learns that Amanda is safe, she gives Gibbs silent permission to kill the Weatherman, the person responsible for the crimes. The Weatherman uses her as a human shield until Gibbs fires into Lee's abdomen, the bullets passing through her body and killing both of them. In the course of her espionage, Lee kills Special Agent Brent Langer and Petty Officer Steve Vargo, whom she was blackmailing for the aforementioned classified information. Director Vance hints that she may have been headed for a death sentence had she survived in "Dagger".